The only public attempt to measure coinjoin volumes showed, for years, the number of btc going through joinmarket to be much higher than Samourai and Wasabi combined. Now, I think that statistic is misleading (also that website stopped reporting a couple years back) but, bear that in mind - unless you have concrete data you shouldn't be too sure.
Discussion
I suppose you're more talking about people moving to JM from the other system ... I guess mostly I agree, then (though obviously we'll never get any data on that).
I hope you don't take it personally, these are just my takes without filter. I always respect devs putting in work and love in a good cause regardless of outcome.