@nine2 IMO it's because new players start with 0 rating. The issue is, I think, that hidden behind that zero is a rating of 1500 +/- 1500, which is actually a pretty high rating. Most players have an uncertainty of around 200-300, so really the rating that new players start as can be thought of as being around 1.2k-1.3k. That means most new players, unless they have significant prior RTS experience, will lose the majority of their initial games. I think that's pretty discouraging for a new player.
I remember when I first started on FAF in like 2015. I played around a hundred games before I quit for 4 years. For a bit of background, I had pretty good general RTS experience: having played a ton of Starcraft 2 (diamond 1v1), Supreme Commander 2, CNC3, COH, etc. I had even played a ton of FA skirmish and campaign and watched like 50 Gyle videos.
I played exclusively teamgames (Gap of Rohan, random 4v4s, mostly whatever lobbies were available) and lost the majority of games I played. I am almost certain my winrate was <50%. I'm pretty sure I started off much stronger than most new players on FAF, so the experience is probably even worse for your median new player. Also, I think hosts can and will systematically stack games against new players (as I think was the case for my early games) - taking away some of that power could help too. It was pretty discouraging - I know you shouldn't expect to start playing and be good at the game, but in a lot of other games you start at a low rank and you can win your way up. First impressions matter, and I think the impression of the first few games will determine whether someone stays on FAF or leaves.
Maybe lower the actual rating players start at, so they have a higher chance to win the first few matches they play? Not sure how that would affect the rating system overall, and perhaps FtX developed an aneurysm just reading this suggestion, but I think something like this would make the game more accessible for new players.
Also, on the flip side of the coin, one thing that kept me on FAF - doing well and seeing my games casted. BRNK casted a game of me back in like 2015, where I did well and outperformed my 1600 mirror in a 4v4. I was super hyped and probably watched that cast from start to finish like 5 times over the years. More recently, Jagged casted a 2v2 game of me in like 2019 where I carried 1v2 against some random 2300 noob. That was super exciting and gave me a pretty big impetus to get good at the game. This would be up to the caster, but maybe Gyle could start something like Low Elo Legends in AOE2, featuring entertaining gameplay from noobs. Getting featured in a cast and watching yourself on the big screen is a big part of the draw IMO.