While I see your point, you did go through SIX of them, not one. It would be a different story had you used the same amp through all of that same time period.
I could buy 6 vintage Chevy trucks in a row and tell you how reliable they all were while only driving then for 20K miles each. But had I put an additional quarter million miles on ONE vintage truck during the same time period, the conversation would have been different. However, a NEW Chevy truck getting a quarter million miles of use is not news whatsoever. (My '99 is close to that and is still my daily driver.)
(Hey, am I the first to get a car analogy into this thread???? Woohoo!)
The point is, if new players, inexperienced in working with tubes, or listening for signs of wear and tear, can get the same tone (or reeeeeealy close) with a brand new, under warranty amp, it is a win win for them (before you even throw in the forty pounds lighter thing).