Most people do use optifine though, and the particles don't cause that much lag. For the majority of the player base, trails won't have any negative effect.
Actually, particles do cause a good amount of FPS lag lol.... I can say from personal experience. From Desktop to Laptops, I always had problems with particles and would have them decreased. Not everyone uses Optifine. "Majority" you're not considering the rest of the community.
It could be different plugins possibly? And I guaranteed that if you ask a random Mineverse player, they probably use optifine. I am also confident that the majority of the community uses optifine. Some people don't use it, but most people do.
My point is, not everyone uses it. You're missing that part I don't understand how. & No it's not "another plugin" causing players FPS lag. Like I said, from personal experience. Particles had a big impact on FPS.
You're missing my point that we should look at the majority of the server instead of the minority, I get that not everyone uses optifine, but most people do. And that's a good point, you got me there. From my experience trails don't cause fps lag, but if there are trails that cause a lot of lag, they can always be disabled by the server.