The reality is that vanilla isn't going to solve lag issues like plugins do. The only real reason in this thread to keep going with pure vanilla is in Crafty's replies: time.
The flipside of that is the other reality: profit.
The server currently doesn't run in a way that will hold onto players. Right now we *prefer* when there are about 6 players on, and that's not how you want a server population to be thinking.
Even when we consider the (better) 1.13 performance on Crafty, I just tried another raid/grief-friendly 1.13 server in the US. I'm connecting from Australia and the difference is simply unbelievable. Not one block lagged, even digging with bare hands. At least 80 players on, since 80 is all that could fit on the screen. Mobs moved fast. Tick speed was actually running on time. I didn't know online games could feel that close to single player. It was unbelievable to me while playing but maybe that's actually normal. With over 80 players.
Even in 1.13 on Crafty we didn't get anything like that. A server on vanilla will tick more slowly more often. It doesn't matter what Mojang should do; they aren't doing it.
If we can still play the vanilla experience with simply less lag, I'm for it. I love the legit vanilla experience, but we don't have to hold onto a bad thing just because it's been held onto for so long already.