In 2019 MLS had arguably the perfect Playoff setup. It started October 19 and ended November 10 and fit exactly in between the October and November FIFA Windows.
Then 2020 and 2021 were altered for Covid.
In 2022 they had an arrangement similar to 2019 except they started and ended a bit earlier to conclude before the World Cup, plus the FIFA windows were different as well.
What forced the change in 2023 was not AppleTV, or wanting to give every team a home game. Those affected how things changed but did not force a change. The format was forced to change because of Leagues Cup. Leagues Cup was deemed more important than anything else. MLS forced everyone to play shorthanded double game weeks during the Gold Cup because Leagues Cup was the priority. The whole season shut down for more than a month, they added even more DGWs besides the ones during the Gold Cup, and they still finished the season late. Decision Day in 2019 was October 6. Decision Day in 2022 was October 9. In both instances you could run a complete single game elimination Cup tournament without pausing for International Breaks. It was perfect.
But MLS and LigaMX wanted Leagues Cup, and so Decision Day in 2023 was pushed back to October 21. There was no way to get to the MLS Cup Final before the November 13 FIFA window. That inevitably meant change and then without the need (or option) to squeeze everything in to 3 weeks, new possibilities opened up, including Best of Three.
Why not just go single elimination again even with a mid-playoff gap? Because if you have round 1 a week after Decision Day on October 28, then the conference semifinals would be a week later on November 4, then Conference Finals a week later November 11. Then you are forced to keep everyone inactive for two weeks at the worst possible time before the biggest game of the year. You also risk having known MLS Cup Final players injured on national team duty. Plus, that means MLS Cup happens November 25 Thanksgiving Weekend, aka the biggest College Football day of the year. Or you push it back another week for a 3 week gap between Conference Finals and MLS Cup.
Blame Leagues Cup. Don't blame Apple, and don't blame greed unless you recognize the greed was wanting Leagues Cup rather than expanded playoffs.