You can't just say "Exeter are doing very well as a club - we should cap more Exeter players; you need to identify who.
IMO Exeter have been great at getting the absolute best out of good-but-not-brilliant players. Their track record with brilliant players is... a work in progress.
Hepburn, Moon & Williams simply aren't as good as their competition for England.
LCD is plenty involved, but George and Hartley simply have (had) better basics. You could argue that Dunn also has better basics, (but way less international pedigree)
I'm coming round to Jonny Hill since the restart - but (a bit like Ewels) I don't get the impression he'll manage to step up to international rugby well - but (less like Ewels) he's earned a shot at proving me wrong. He should certainly be in the conversation. I'm not sure he's earned a shot ahead of or top 4 locks before this Autumn though.
In the backrow - Exeter's players are hamstrung by the specific system that Exeter use. Baxter just sets them up differently to any other coach. I feel that if Simmonds had been playing flanker for the last 6 years, he'd have been capped earlier, and had a much better chance at staying in the team. As it is, he's in a position of real strength, and his attributes are better suited to a position he doesn't play.
Much has been made of Maunder - but he's never kicked on. He's reaching that point that Spencer was in about 5 years ago. He's losing too much development time by not being first choice - he's also not quite earning first choice where he is.
Joe Simmonds should (IMO) be England's 3rd choice FH - maybe 2nd if he takes to international rugby well - Eddie only takes 2 FHs, one of whom is now the captain. Behind that he likes brining in apprentices at FH. Unfortunately for him, 3 years ago, Smith was way ahead of him, whilst being 2 years younger.
Devoto should have been involved more - and may have been were it not for injuries
Slade is plenty involved - but plays in a position of strength for England (and, as has been said before - had he spent the last 6 years playing in his more natural position, he'd have 50+ caps and be automatic starter by now)
Nowell is plenty involved - but plays in a position of strength for England (and, as has been said before - his natural attributes probably suit a different position better, and he IS hamstrung by his pace on the wing; and however much good he does, picking him means dropping at least one of May, Watson or Daly, all of whom are or have been world-class on the wing).
As ever - it's not just "who deserves to be picked" but also "who should be dropped to make room"