I'd like to clarify the 8-win part to start with. It's no team with 3 or fewer losses rather than 8+ wins. There have been two 8-4 teams that have been left out.
2014 Idaho State went 8-4, best wins over two 7-5 teams, lost two FBS games and to two playoff teams by 3 and 5 points. However, they beat two DII wins so they only had 6 FCS wins. Guessing they got dinged for that.
2013 Youngstown State went 8-4, best win at 7-5 team by 1, lost FBS game, by 18 to No. 1 NDST, by 29 to 8-4 SDST and by 2 to 7-5 Northern Iowa. There were only three 8-win teams in the conference that year and most of the teams played 12 games.
Here's another stat. Since the playoffs expanded in 2013, the Big 3 conferences have gotten at least 11 spots each year but 2013 (got 9 that year) and at least 12 each year from 2014-2018. In 2019 they only got 11. We're ignoring 2020 since it was a smaller bracket.
So if you give the MVFC 5 and the CAA 2, the Big Sky could get 5 and that would still only be 12. The third best team in the CAA is either 6-5 Elon (lost to JMU by 24, Nova by 35 and a 1-10 Wofford team at home by 2) or 7-4 Rhode Island (didn't play JMU, lost to Nova by 44 and other three losses were to two 6-5 teams and a 4-7 team).
There are two conference champs who get autobids that are unranked. However, it doesn't appear the Ivy participates so that takes out No. 20 Dartmouth and No. 24 Princeton. The SWAC plays its own conference championship game so that takes out No. 19 Jackson State.
Mercer is ranked 21 in the STATS poll. They just lost at No. 8 by 3 so they'll probably remain there. Finished the year 7-3 but one of those was an NAIA win. Best team they beat went 6-5.
Stephen F Austin (8-3) is ranked 22 in the STATS poll and won 42-6 this week over a 2-9 team. They lost to Sam Houston by 1. but also lost to a 5-6 team. One win over Lincoln (CA) that I can't even find info on. Beat a 7-4 team as best win.
Others receiving votes last week. You could sell me on 6-5 Northern Iowa (26) as being better than us with a better resume. 27 is Monmouth (7-4) who lost 49-17 to the only good team in their league and by 30 to Holy Cross (28), with their best win being over a 6-5 team. Holy Cross (28) beat Monmouth and UConn, which is a FBS win in name only. VMI (29) just lost again. Chattanooga (30) also just lost again. It doesn't get any better either if you keep going.
TL;DR: I know we're down on the team because of how we finished but once you get into the 20's in the rankings, the quality of team drops significantly and we're better than those teams.