Because 40 odd years ago, even 'journeymen, sparring partners' had a bit about them, and could/would offer some very good learning/experience, proper rounds of sparring/fighting.
Magoo, seriously, have a look at wilder's resume, NOT just his record, but RESUME. You will quickly see he's fought NO-ONE. His biggest test BY FAR, is fury. And he's lost 3 out of 3, yet he still put fury on his arse what, 4 or 5 times in 3 fights?!
Then have a look at fury's resume, and you'll also quickly see, that apart from klitschko, who didn't want to fight, that wilder is fury's best result! f***