You've had good experience of using fusible products, that's great, but it's not everyones experience
I hate to beat a dead horse, but it's not your experience you're basing an opinion on. Old, beat-up clothing and your tutors (who may or may not have had a vested interest in teaching you tailoring) showing you samples of what to expect when you use a fusible are not the same as actually using the product.

The fact remains, fusible interfacing, chosen correctly, applied correctly will last many years with nary a problem.

I am not trying to push fusible interfacing on you by any means, your craft is at a level both higher and older in tradition that fusibles, but pushing a negative opinion on something that you don't have actual experience in using is just not right.