I feel the issue with Dembele in relation to MUFC of the time when he was at Fulham is that we were accustomed to Scholes and Carrick as well as the beast version of Fletcher, so a lot of players with deficiencies were dismissed because they weren't the ready-made equals of the aforementioned names. It happened with a lot of players at the time we were in need of replacements - any minor holes in their game and they were not deemed successors to the likes of Scholes and the Holy Grail search of the next Keane.
It wasn't just Dembele that suffered because of the standard of player we regarded then. Modric was seen as a joke on here when he was coming up at Spurs, too, with only the poster Scholesy and a handful of others championing him and believing he could go all the way as a player.
When you're setting your sights on the technical acumen of a Thiago or the all-round brilliance of a prime Vidal, it makes sense why a midfielder whose passing was average and shooting atrocious, was dismissed as below par.
My take on Dembele was that we could have worked on his weaknesses whilst benefitting greatly from the strengths he already had in his game. He was always top percentile as a dribbler through midfield and was always a nightmare to dispossess, so even if he couldn't shoot nor pass very well, there would have been nothing wrong in having someone like him getting the ball to other players that could.
Unfortunately, there isn't a youngster coming through with the same skilset as Dembele, but if there was, we should pounce on him because the ability to retain possession and go past players completely changes the way you can approach the game. It forces opposing midfields to plan and accommodate those runs and break rank from their positions to go and double up on the dribbler, in turn, that free up others in the midfield to do their thing. It's not a coincidence Eriksen's level of expression shoots through the roof when Dembele is in the team, and I'd hazard a guess and say that type of player would do wonders for Pogba, too.