Everyone knows silverfish are the most vicious, destructive mob in the game. If people started making silverfish spawners, Minetown would be doomed!

Unfortunately you're incorrect about the Ghasts and Enderdragon's destroying the main world. Explosive damage is disabled (I sat here for 5 minutes trying to remember this word, wtf? I'm dumb). They won't be added due to their rarity of item drop. I mean, of how expensive the item is. Dragon easy to tell (it's a one spawn per game of minecraft, but we reset the end frequently so that's good enough).

I'm also curious about the silverfish? They don't drop anything that I know of?

Silverfish only drop a huge amount of experience for their size.

Oh, I never knew that. I have yet to see one. Makes sense then. I agree, these three spawners should never be seen on MT in the CS.

You want the reasons, here they are!!!

Ghast explosion is NOT turned off in main world...only Creeper explosion...idk if you remember but ranvandorp gat a ghast spawner and they almost obliterated nimaro city...that was not a fun day for me...also...market for tears would be shot to hell

Enderdragons are similar: 1: any block they go thru that is not endstone or obsidian is destroyed, 2: they will cause hella lag if in the main world...also market for eggs would be shot to hell

Silverfish...err...idk? ive actually never encountered a silverfish...so i cant really say...

Silverfish is a obvious no-

What they do is hide in blocks such as stone, cobble, and stonebrick. A spawner would mean enough of the little giaz to hide in every block in the room, and then when you go in for an expansion- Boom! A swarm jumps out of the walls and, face it, you're toast.

The only place that will EVER have a silverfish spawner is a stronghold (If youre lucky enough to find one) and The Minetown Zoo (For obvious reasons)\

Theyre like my friends cat: they look cute! Go over to pet it, and BAM! Your face drips blood all over the carpet.

As a response to Zionia-

My first ever encounter of the zoo was that incident (I never knew we had a zoo until then)

I had started an extermination buisness since mobs are so easy to kill here for me- lag slows em down more than it does the players. I heard Ron advertising on chat, and Stealth and I were there in a flash.

You caught all the ones we couldnt kill. Although no one recognizes me, i think i deserve SOME credit ;P

Silverfish are hellish little buggers if encountered in a stronghold, because they hide in blocks that look like normal blocks. With that being said, if you attack one, all dormant silverfish in a 20 block radius wake up so you can get overwhelmed REAL quick.

EDIT: dam you Pokemon! Stealing my thunder! Lol

Hey- I do my reaserch on mobs. I knew that off the top of my head. I even kinda study em on creative. Silverfishes are pretty interesting. They probaby have the most complex AI of any other mob except blaze.

Quite simply, all three of these creatures are too dangerous, which is why we are not allowing people to get a spawner of them.

Well, even that wouldn't be a huge issue actually. All you'd have to do is have a glass / obsidian box with a spawner in it to both contain them, as well as two - three doors to make SURE they dont escape.

HOWEVER:

I believe, if you "farmed" blocks by having silverfish get into a stone, then used silk touch, THIS could be a major issue.

"The stone-like block that produces silverfish when broken is often used in some servers as a form of griefing, in which the griefer places the stone-like blocks in players' houses, and the player gets attacked by silverfish as soon as they break it. It is also possible to create stairs, bridges or flying platforms out of silverfish blocks. When a player breaks a block (to open a chest, for example), a silverfish will spawn. Inexperienced players will attack the silverfish on sight, resulting in more spawning, which will cause the death or stranding of the player by falling or silverfish attacks. "

Minecraft Wiki: Silverfish

The wiki there has quite a bit on them <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/1f642.svg?0" type="image/svg+xml" standby=":)">:)</object>

Ghast on the other hand, are interesting.

They tend to fly up to, well the sky box, which can be a huge pain to kill them.

You could still make a good trap for them. Obsidian will not be destroyed from them, although you'd need to make doors using sticky pistons and obsidian. This is the same concept of having a TnT proof bunker.

Minecraft Wiki Ghast

For a list of block blast resistances: Minecraft Wiki: Blast Resistance

Also, the use of glass could be used to look into the trap, however must be only 1x1 so there is no chance of the Ghast escaping should it destroy the glass with a fireball. (having more obsidian behind the glass, to form a "viewing room" that is also explosion proof would add another layer of protection)
(Also from the wiki)

In conclusion, the underlying issues are, at least in my opinion, human nature.

Although these spawners could create viable farming solutions for those who are crafty, there is a great chance that they could also be abused, or mistakes could happen that could result in a LOT of cleanup work.

IF (I'm not saying they should, but in theory) their eggs were sold, they should cost a LOT of currency. Hopefully that would only allow more experienced players, and players whom have been on the server for a long time to access them.

Kind of a long read, but if people are interested in it I hope it helped <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/1f642.svg?0" type="image/svg+xml" standby=":)">:)</object>