@172
"What's the underlying reason these misleading terms got set up?"
++ Probably trying but failing to bring order into chaos.
Anyway: 'open games' can lead to closed positions; 'closed games' can lead to open positions.
'Open opening' would be a tautology and 'closed opening' a contradiction.

They could have said ultramodern or very modern or whatever and the terms would be equally useless and soon to be obsolete/ambiguous as time passed anyway ...
Coach: 'don't worry about words like hypermodern - not going to be any use.'
Student: 'but what about 'Open game' in e4 e5 games? Is it because the bishops are unrestricted after those moves?
Coach: 'the bishops are 'unrestricted' after d4 d5 too. No bishops are blocked by d4 d5.
Again - dogmatism of these terms isn't going to help your game. Similiar with 'closed' and half-open and semi-closed.'
Coach: 'These terms might mean different things to different people.
And GMs who are chess book authors might use those terms in the titles of their books and within the books.'
Student: 'but ...'
Coach: (depends on the coach - the precise situation - and how the coach and student choose to proceed.)
But idea: the pitfalls of terminologies.
Idea: The words are to serve us. Not us to serve the words.
In the QGD there's a natural tendency to want to play e3. That isn't the case after 1. e4. e4 is supported by pieces and anyway is more mobile. The nature of 1. d4 is that white very often keeps the pawn there and removes it only if there's advantage to do so. Also, black very often supports d5 with e6. It's less common in 1. e4 ... e5 games for black to support e5 with d6. Hence the distinction remains reasonable, since the word "game" means "opening" in that context.
i wouldn't pay for that coach, except to go away.
Fact still remains that the bishops are 'unrestricted' after d4 d5.
And - bishops can get out before e3 or e6.
And - after e4 e5 ... d-pawns can still be played to d3 and d6 as opposed to d4 or d5 ...
And f-bishops can develop to wherever before d3 and d6 also.
'open game' and 'closed game' sets up internal contradictions ...
why limit the student?
What's the underlying reason these misleading terms got set up?
Probably because 'open' and 'closed' are commonly used terms in language.
So words were served instead of objectivity.