I think this is one major issue for Halo and arena in general where the hardcore players and teams just dominate matchmaking which turns new players/teams away from long term sticking with the game. New modes and maps should help alleviate such things, for awhile at least, but it's intrinsic with most FPS fanbases these days. A buddy and I tried to go with COD Warzone recently and I'm just getting my ass handed to me across the board e.g. I don't know the maps, buildings, meta, loadouts, camping/anti-camping etc. I've never really played COD TBH. I realise Halo and games such as COD WZ alike have these decades long dedicated players just wrecking the population for the most part. There is a large learning curve to such games and I think it's something developers struggle with. How do you bring in new players but reward your dedicated hardcore simultaneously?
When I compare the designed gameplay elements, maps and beats of say Fortnite and Apex there is insight to what and why things are implemented as well as received successfully by large populations. It's more than just being on so many platforms and devices as I feel it's designed from the outset to lower that learning curve initially and for say some weeks or months with the game but still presenting a large skill gap for players and teams to be rewarded or years e.g. less punishing to learn and similar rewards for playing well solo or with a team over time.
Things like revive, respawn, gulag, buy backs etc all go some way to allowing players/teams second chances while delivering players back to matchmaking pools often. This is where I feel arena games are losing out to BR style games, it's that end game that rewards the dedicated players but the quick and regional matchmaking of population pools from player recycling of lesser outcomes/skills.
No matter how well Infinite designs gameplay and maps if they're not integrated with optimising this balancing act of new vs skill, solo vs team and region vs pools they're dead in the water over time in terms of fast matches and quality connection in games. All of that combine for player experience and it cannot just be focused on esports or USA again. Halo will fail hard if they go that route again. Of course the MCC/H5 systems have matured since then so I expect many of those issue will be far more optimised and help attract/retain more players from launch initially than any other Halo release.
