A lot has changed since the 1980s. RAM access is much higher latency (in cycles), we have tons more RAM, and programs use more of it.

Maybe it is still possible but "we did it in the 80s so we can do it now" doesn't work.

Vypercore were trying to make RISC-V CPUs with object-based memory. They went out of business several months ago. I don't have the inside scoop, but I expect the biggest issue is that they were trying to sell it as a performance improvement (hardware based memory allocation), which it probably was... but also they would have been starting from a slower base anyway. "38% faster than linear memory" doesn't sound so great when your chip is half as fast as the competition to start with.

It also didn't protect objects on the stack (afaik) unlike CHERI. But on the other hand it's way simpler than CHERI conceptually, and I think it handled temporal safety more elegantly.

Personally I think Rust combined with memory tagging is going to be the sweet spot. CHERI if you really need ultra-maximum security, but I think the number of people that would pay for that is likely small.