To say all time is too premature for that claim. You’re talking about thousands of fighters since the beginning of the sport until now. Ilia has crisp boxing but he hasn’t wiped out his division yet. Just because he KO’ed Volk and Max doesn’t prove he’s the best striker.
Max is a great striker but he was getting a run for his money against Yair on the feet, got out boxed by Dustin, and got out struck by Conor. Before Volk got that clean counter on Yair, he was wrestling him the entire match. Styles make fights, and maybe someone like Yair or Edson Barboza at 145 can pose different threats to Ilia. In their current position, that will not happen.