They don't work out for us either, do they?
Mata, Shaw, Schneiderlin, Sanchez, Wan Bissaka, Maguire, Matic, Sancho (is a PL product), Mount - all have ranged from mediocre to shit. Shaw has shown the most potential but has been fit sparingly to display it.
I don't think that list proves much, other than we are just bad at picking the right players at the right times.
Shaw - Absolutely the type of player we should go for. I don't think his injury troubles could be predicted at the time.
Schneiderlin, AWB, Maguire - Bad scouting, as they were never that good.
Matic, Sanchez, Mata - Good players that we either got too late, or didn't actually fit what we needed. Matic in particular was very good for a period.
Mount - Partly injury problems, but still a baffling signing at that price.
Sancho - Doesn't apply, as he never played a PL game before joining us.
There is plenty of quality in the PL to go for, if you identify the right players. Our rivals have partly built their success on this. Liverpool with the likes of Robertson, Mane, VVD, McAllister, and Jota. Chelsea with Neto and Caicedo. Arsenal with Raya, Ben White, and Rice (could maybe add Havertz). Man City to a lesser extent, but still got Mahrez, Ake and the like. Of course, they haven't gotten everything right, but there is quality in PL signings that is worth paying for. Most of these would have been successes for us too, and some were the type of players we should be desperate for.
Where it tends to have gone wrong is when clubs overrate and overpay for English players in the Premier League (Maguire, AWB, Grealish, Phillips). Declan Rice is the only recent example of a big money English PL signing that looks like a success, that I can think of.