Not a fan of how Blizzard treated Classic but you’re woefully ignorant about a few facts.
There are no dead Classic servers. Blizzard released mega servers which hold tens of thousands more players than Vanilla and they’ve stated a medium pop Classic server’s population is bigger than a full Vanilla server.
Some servers still have a queue during peak times.
And why would you bring up retail servers? Retail is nothing more than one big CRZ mess and servers don’t matter.