I fully conceded that the relying mostly on the RPI is a mistake and has resulted in teams that likely shouldn't have been in the tournament in 2022 and earlier. My alma mater in 2016 and 2017 are probably prime examples.
RPI is composed of a team's top 10 RPI games. All ND had to do was schedule one more game and it would have pushed out one of either the 1st SU game or the Marquette game out of the RPI calculation for ND. ND had two free Saturdays weekends where they didn't play.
Should ND have gotten in? Yes.
Did ND hurt itself by not scheduling at least one game? Yes.
But, your points on the Ivy don't support your argument. The ACC, which year over year is the best conference, has had times when all 5 or 6 (when it was a 6 team conference) get all their teams into the tournament. All of those times were based on the RPI. Not all of those teams played in the 4 team ACC tournament. For example, in 2013, 5 of the 6 ACC teams made the NCAA but there was only a 4 team ACC tournament. My point with the FF was that only 3 teams came within 5 goals of MD - Cornell, Princeton (didn't make the Ivy playoffs) and ND - this year. Cornell played awful in the 1st half but made it a game in the 2nd half. The demonstrated they could play. The Ivy went 9-5 in the tournament. (1 win and 1 loss was an Ivy match-up). Otherwise, 2 of their 4 other losses where to MD.
If you want to point to a team that shouldn't be their point to OSU. If ND beats OSU earlier this year, ND is probably in and OSU is out.