Keep in mind the population of those who post on online forums about therapy is small and self-selected. Reliable statistics can’t be extrapolated from a sample like that. Certainly not enough to say “most.”

My own experiences as a client and reading on here suggest a far more mixed conclusion. Sometimes therapists leave, sometimes they don’t. Sometimes the client leaves. Sometimes both stay but the relationship is broken. Sometimes it heals and is stronger. Sometimes therapist and client part by mutual agreement.

But anecdata is almost worthless to support the point you’re making.

ETA: not, of course, dismissing anyone's individual experience.