In the 80s and 90s academia and high-end computing was taken by a RISC illusion. RISC architectures were simple and clean and easy to implement at higher performance than any CISC processor of the time, so people assumed that of course RISC would be the feature, right? Well, no. CISC, or, to be more truthful, x86 was a mass-market item with competing manufacturers with deep pockets (like Intel and AMD).
In the mid 90s both Intel and AMD broke RISCs neck (though it was not immediately clear perhaps what a groundbreaking innovation this was): They introduced processors that translated x86 instructions to other instructions (µops) that were then scheduled and executed. Turns out, this is pretty efficient for a number of reasons (1- you get existing software 2- x86 code can be really dense; RISC had instruction bloat issues 3- decoding insns is only a very small part of what a CPU does and does only consume a minority in transistors 4- you can change the µops, they are an implementation detail, to best suit the exact core at hand; something impossible for RISC). This allowed x86 all benefits of what RISC previously had for itself.
By ~2000 most RISC architectures were dead (Alpha, SGI, ...) with only POWER and SPARC surviving in their niche markets.
In summary: The importance of the ISA was vastly overestimated by researchers, who assumed that this was a blocking issue to make x86 go faster. In the end, x86 won, because x86 had the bigger market with more money in it.