This is a bad starting point.
Most of these so-called "sins", if "purged" from map design overall, would stiffle their design overall and make most maps excessively similar and standarized. And you don't want 100+ same-y maps.
These bullet points are really individual, judgmental and single-tracked. They don't consider other aspects of the game outside online competitive play. These aspects are less so bad, and moreso
inadequate when put under this very specific context and when used in their very specific current ways, but if they are adequate within the context they were meant to be played on (casual vanilla deathmatch), then I don't see any reason to call them "bad" or "sins". That approach only makes it look petty and one-sided.
I do believe in the idea that if it's good in a non-objective based team mode (tlms, tdm, the likes), it's good for lms and dm. It's why I don't like the talk about a map only being based on dm, especially in a game like this where team modes correlate good maps (MM9DW1 MM7DW1 MM8DUO MM5DAR are all great for team modes and deathmatch).
That idea is true and I agree with it, but using certain maps as examples of this is not appropiate: they are unintentionally accesible. The fact that they're good in a different context is an accident because they were designed individually and separately from online competitive play or non-"casual deathmatch play", and were actually made with the exact same intention and context as the "bad" maps with "sins" were made for. Some maps probabilistically will fare much better than others in non-intended gameplay because there's so many and some have approached map layout in a different way than just plain deathmatch arenas. This doesn't mean all maps must follow their specific example so we have 100+ MM5DAR lookalikes, but their "accesibility" on other game modes would greatly help in paving the way for other maps to become compatible.
A much more helpful and attractive discussion would be to pinpoint exactly what makes a map "accesible" for all game modes (something I think should be the goal of 8BDM maps, despite the main focus of the base game, which yes its a strong argument), instead of starting from "map sins" and putting very specific examples of maps that flow well in a very specific environment. The smart play is to play around the "sins" and solidify "pillars of good map design" that encompass more than just one specific playstyle, rather than "purge" these details as if their very existence is a toll on the experience of the game, which is assumed to be just online competitive play.
If a map designed for casual vanilla deathmatch doesn't flow well in online competitive play, that doesn't mean it's bad. Put it on a banlist (which is also not bad, BTW) and bring forward a helpful discussion on how you can make some maps better based on good examples rather than by labelling "sins". None of these are "sins" if they are added properly and mindfully.
This is a baaaaad starting point, and would honestly recommend you to change the title of this topic and rethink your approach and rhetoric. Your intentions are good, but this is not a good way to start.
also hi