Yes, of course they can. They can stop development and scrap the game too if they please.
You have it wrong man, you bought a Game knowing that it is in Alpha and they stated that everything is subject to change. Sorry man, you just need to live with it.
Servers don't save the quality nor "global quality" man, Servers only saves the position of everything in the game and the Client renders it (with "global quality").
The issue you are experiencing is completely client side and not server side, meaning that they won't be able to create a server to help with your PC's fps. You just need to face the facts and upgrade your PC
They already added the potato setting... if your PC still struggles on this then it's time you upgrade your PC. Like seriously.