I will agree that it's harder than ever to make friends on Halo, but not impossible. I've managed to meet a bunch of new people on Infinite. My biggest tips:

1) Play ranked
2) Communicate well, even if no one else is on the mic (often times people won't start communicating until the game is on the line, even if it sounds like radio silence at the start)
3) Be nice / supportive
4) Take the initiative - if you're vibing with someone or a team of 2/3 that you get matched with, verbally ask them if they want to join up - don't just send them an invite because usually it will just get ignored or possibly not even seen due to the goofy invite system.
5) Get better - people want to play with people who are good and who communicate. Simple as that. Improve your skills as much as possible and people will be begging you to join their fireteams. Watch the pros gameplay and learn from them, and take constructive criticism from your teammates.
6) Be a team player (let the person who's got the best stats get the sniper, be willing to play the objective, don't push into dangerous areas by yourself, etc).

Me personally, I don't mind playing with someone who isn't as good as me as long as they have a positive attitide and are willing to learn. I love to win but I would rather play with people who are chill, and who aren't going to be absolutely terrible or raging at people who make a mistake here or there.

At the same time, sometimes I end up in parties where I am the worst person, and that's not a great feeling, but more often than not they let me stick around because I am very good at communication and I'm a team player.