True but a lot of these kids are rejecting contracts at clubs like Utd now unless they get silly wages, Chelsea are signing most of these kids to £30-40k a week contracts and in the case of Zouma a lot more before loaning them out. Say we give him a 3 year deal on £20k a week that's £3m we'd be committing in wages to a kid who I think we all can agree has a small chance of making it if a lot goes his way. I think the kids now are wary of getting trapped in the loan system they want to see a light at the end of the tunnel which is why a guy like Solanke rejected a new deal at Chelsea and so did Chalobah, there's also talk Sancho will leave City.
I think to break into top sides now you have to be a Rashford though you have to be as good as the first team guys at 18/19 years old and go out and prove it on the pitch if you want to surving at a club like Utd. Some like Lingard, Cleverley, Evans or Welbeck thrive through the loan system and it really works for them but others like Wilson or Borthwick-Jackson it can stall their progress. You also have to consider that there are lads like Gomes coming up from the U18's this season who may already be better than him, you do have to make ruthless decisions at this level.
You are right about Watford's was just throwing a name out there as I know Marco Silva has the same agent as Jose.