Yes, it's great when you are able to combine the two in a game like 5e (accessibility for new players and familiarity for old players)...
It does seem to have hit a good compromise between the two this time around. The comparative lack of visible 'bloat' avoids scaring off potential new players, and is familiar to returning players from 1e, while the content is familiar enough for returning players from both d20 and the classic game. The accessibility of the content is another issue, but it's certainly better compared to 3e or, especially, AD&D (1e was outright designed to be hard to understand & master, the philosophy being that the DM /needed/ to know the rules better than his players).
I think it's safe to assume the game is pulling in both new and returning/retaining old
The recent age-range statistics also seem to back that up. It's not just a lot of elderly grognards who started at the height of the fad. They're the #3 cohort of 5e players. It's a great thing.
I choose not to speak to what happened with 4e
Good, you have a poor record on that score, in any case.
But, I did play & DM 4e for it's full run, and introduced a lot of people to the game in that edition, and in the previous ones back to 1e. And, IMX, the game was never as accessible as it was at the start of the Encounters program. The retention and the ease with which new players transitioned to DMing was remarkable. What was lacking was retention of returning & long-time players, and, of course, the wealth of new players to retain in the first place, as there wasn't a boardgaming renaissance drawing hordes of people into the general orbit of hobby games at the time, as there is now.
In that case, you (the specific you) were simply wrong in your statement. If the reader, in general, were feeling excluded, inclusivity would be poor, indeed.