I've not read the whole thread. But my answer to your question has a few parts.I'm not looking for absolution as much as wondering how other people were playing back then, and if EGG and company meant the same thing by "roleplaying" as we do today.
(1) Gygax, by role, seems to have meant something like "function". So on p 18 of his PHB he says "The approach you wish to take to the game, how you believe you can most successfully meet the challenges which it poses, and which role you desire to play are dictated by character class (or multi-class)." There is an implicit contrast here between the single-character approach of RPGing and the control of a whole army - and thus of all the roles/functions - in a wargame.
(2) From very early on in the hobby, there were players departing from this conception of "roleplaying" - ie who focused on the role not as just class/mechanical function but personality, characterisation etc. This comes through clearly in discussions on RPGing in the late 70s and earl 80s White Dwarfs (eg @lewpuls had very interesting discussions of these differences of approach).
(3) A further difference that is important to me is between role as characterisation and role as protagonism. I tend to find a lot of RPGing material and discussion tends to emphasise the former. Whereas I am more interested in the latter. In some ways this comes back to Gygax's idea, but instead of looking at the role/function through the lens of challenge it is looked at through the lens of theme and story.
Here is a thread I started some years ago now that deals with some similar issues to yours: D&D 5E - What is the "role" in roleplaying