Using bracket pools as a justification for why making Dayton doesn't count as making the NCAA tournament is pretty stupid.
The people running the pools could easily add the Dayton games if they wanted to - but it is easier and cleaner not to and it gives people a couple more days to fill out their brackets.
You do you but I think the semantic argument is dumb and a waste of time. The goal is to get into the tournament because it makes you relevant and gives you a chance to be mentioned and discussed, a chance to win and advance, a chance to, in a dream world, make the final 4 and maybe win a championship. Does making Dayton do those things? Of course it does.
From wikipedia: "Played mostly during March, the tournament consists of 68 teams..." "The tournament teams include champions from 32 Division I
conferences and 36 teams which are awarded
at-large berths." "The tournament consists of 68 teams competing in seven rounds of a
single-elimination bracket." "The
Selection Committee determines the at-large bids, ranks all the teams 1 to 68..."
Wikipedia also refers to the Dayton games as play-in games and the next round as the first round, but, again, these are semantics. They have to call those awkward first games something.
Through the years the tournament field has been all kinds of weird sizes - 22 teams, 25, 53, whatever - with formats including small first rounds, teams getting byes, etc. Did teams that barely made the field and didn't get a bye or had to play in a "play-in" game or whatever argue about whether it really counted as making the tournament? I seriously doubt it. The NCAA decides the size of the field of its tournament - they have decided it is 68 teams and either you are one of those 68 or you are not. It is only 68 because they kept adding conferences that would get automatic bids, even though those teams are much worse (resume-wise) than many of the at large teams. So they added 4 spots to make sure deserving at large teams didn't get left out. And then, just for giggles, they decided that the 4 lowest ranked at large teams should play in Dayton instead of just putting the 8 lowest ranked teams there - because they knew the 8 lowest ranked teams would always be 8 of the conference champs from the worst conferences... There are 36 at large teams so making Dayton as an at large team means you are probably ranked in the top 40-45 teams in the country - whatever that is worth...
I just wasted way more time than this argument is worth...
Either you get the chance to advance to the final 4 and beyond or you don't - making Dayton gives you that chance.