The other side of that coin is that if you required "technical implementation merit", then only people or groups who have strong experience with C++ compilers would be able to propose things.
I'm not saying that the existing situation is ideal and it's certainly not a dichotomy, but you have to consider the detriments as well as the benefits.
Great, languages like C++ relevance on the industry, should have a "you should be this high to play" entrance price.
Also I should add this is no different on wannabe C and C++ replacements, or most other programming languages with similar market share.
Go try to do a drive by pull request for a new language feature on those ecosystems.
You could have a two-stage process. Stage 1 would be the proposal, where you have the discussion on whether the feature is desirable or not, which can then be provisionally accepted. At this point it is not in the standard.
Then you have Stage 2, which would require an actual working implementation, so it can be properly tested and such. Acceptance in Stage 2 would result in the feature being in the standard.