The thing is, with the new Monero's randomX update it makes a lot of sense to mine with CPU. Browser mining is less efficient, true, but you don't need any apps or install anything so it's also easier for a casual user. I think the value is there if the users could set by themselves how much threads they want to use, but it will probably not be "profitable" in any shape or form anyway.
RE: Project Idea: Mining pools for Steem