Which part is not true? I'll accept 'exaggeration', because pristine is probably not the best word, but it absolutely becomes harder to pass all of the criteria for a trial once you start getting deeper into treatment (e.g. 4+ cycles of chemo). This is particularly true for immunotherapy trials, but things like brain mets can disqualify someone from a huge swath of trials, regardless of how active they are.

This all makes sense if you're looking at trials as a way to determine if a therapy works. If you're looking at them as a way to access experimental medicine, however, it is pretty disappointing.