Some fans just have an in-built hostility to young players. Same across the whole country. We just don't have the same culture of developing young players that the other major footballing nations have. Hopefully that will change with time.
It's called short-termism mate. Premier clubs, and sadly a large portion of their fans, demand success (relative to their status of course) immediately, and I can understand that to a degree given the financial rewards of just being in the premier league.
For good young players to develop they need to be challenged, and the good ones won't get this playing youth or lower league football. They also need to be given the opportunity to play alongside top class players so they can learn from the best. There is also an old adage that says the quickest way to learn is from your own mistakes.
Therein lies the problem. Young inexperienced players make mistakes. They are also notoriously inconsistent. Premier clubs, and their under fire managers, are extremely reluctant to accommodate those mistakes as they pursue success, whether that be measured by survival, European qualification or trophies. So unless young players succeed early like Lukaku, Dele Alli or Hazard, clubs won't take a chance on them. So invariably they don't develop.
In other countries, Spain, Germany, France, even Italy, clubs introduce their best young players to the first team squad each season. Even the top ones. Some clubs even run their finances based on the policy of bringing in young players and developing them. However, it will take a very brave Premier owner/board/manager to build a team around a group of young players and see them grow together.
Everton have a tradition of bringing through young players, but lets be honest with ourselves, in the vast majority of cases it has been injuries that has given them the opportunities. The likes of Holgate, Kenny, Lookman, Vlasic and DCL wouldn't have got near the first team had we a half decent squad or had injuries to key players. And the ones who had earned their spots, Barkley, Stones, Dellboy, Davies, were hounded all the time for their inconsistencies and mistakes. Even Lukaku had his regular detractors and he was the best striker we had at the club in 30 years.
We have an opportunity here to try and build a team around this current group of young players. Six in the England U21 squad plus the likes of Beni and Vlasic (who I see has been dropped back down to the Croatian U21 squad). But TBH, I'm starting to give up on the chances of this ever happening, especially whilst the club continues to employ the likes of Allardyce as manager.
In fact, I'll think you'll find that more and more of our young English stars will follow the example of Sancho from City and pursue their development in Europe. English youth is the envy of world football at the moment, but don't expect this to be reflected in the future prospects of our National team, as it did with the likes of Spain, Germany and Portugal.