When games had less strict SBMM you never knew if you would be the worst or best player in a lobby. It also allowed for your performance to steadily rise over time as you got better because if you were above average then more often than not you would perform above the average in any given lobby. Every now and they you would clearly be the best or the worst in a lobby.
If you played in a group (either friends or stuck around in the same lobby [which lets bring lobbies back]) as the match played out you figured out who was better and worse than you on your team and the other teams you played. This lead to almost man to man gameplay as you were trying to beat your counterpart on the other team. Sometimes this meant protecting those worse than you, grouping up for safety, or protecting the best player so he can do whatever it is he needs to do (take a new position, grab a weapon, or get on a kill streak).
Games felt more diverse and if you got good you could actually do very well most games which felt great.
It felt like playing pickup basketball at a local park. You just played with those nearest you. Now Strict SBMM has made it feel like once you practiced and got better than most people at your local park, you now are shipped into a ranked league at another park far away to play against people right at your skill level.
Its frustrating because you were just trying to play a game of pickup but now you are basically in a league. Sure ranked should have Strict SBMM but social should definitely prioritize connectiok first. People used to not be so soft and realized they would probably get stomped for a bit as a new player until they learned the game but for some reason we have to coddle new players and not let them see people better than them in the same game. One of the ways i used to try to improve was to watch kill cams or follow better people than me to see how and what they did to be so successful and now thats just not really a possibility.
People need to get over the fact that players are going to be better than them. I always had fun in MW2 back in the day even if I got nukes dropped on me or was able to go on a 20+ kill streak. The gameplay is what made it fun not just how well i did and for some reason people nowadays and devs seem to think we can only have fun if everyone has at or near a 1.0 kd and a 50% win loss ratio.