As someone that plays a lot of different competitive games, I see exactly what he's talking about A LOT when it comes to switching to a new iteration in a series of games.
Street Fighter 2/Alpha players HATED Street Fighter 3 when it first released. But now you ask a die hard Street Fighter player what their favorite Street Fighter is and a lot of them will say SF3. It was the same thing when Street Fighter 4 came out back in 2008/2009. They added this "come-back" mechanic called Ultra's, inputs were much much much easier and a lot of people simply didn't like the "Focus Attack" system. The Street Fighter 3 players thought it was baby-mode Street Fighter and a lot of pro players even retired or stuck to SF3. But now you look back at it and SF4 is actually quite beloved. And it seems SF5 has a lot of players that are complaining about how things are different from SF4 and the cycle is and will continue to go on and on with every new iteration. Its practically human nature.
Counter-Strike Global Offensive also had this same issue with 1.6 players. A lot of people retired(and some are trying to make come backs in GO now but they are way too far behind) when Global Offensive became the main focus of the Counter-Strike series. And as someone that played GO in beta, I'll tell you that CS:GO was A LOT worse off than Quake Champions. There were fundamental issues with the game and it took a mountain of patches to get it to a place where the game was enjoyable.
Just to clarify, I do think Quake Champions WILL have its fair share of problems that will need to get fixed and I think the community is going to be absolutely vital in making the game what it needs to be. I think this game will live or die, not by whether this is a good game out of the door on release date, but instead by how good the community is at communicating with iD and fixing issues. There WILL be issues. Whether its bugs, balancing, map layout, design. There WILL be issues.
If you're that die hard Quake player that wants this to revive the competitive Quake scene and you miss Duels and you miss big tournaments with pro players showcasing their best talents then I think you have a responsibility when you make your criticism. When you see something you don't agree with, take a step back as a player and try to understand what iD is trying to achieve with their decisions and try to understand why something exists the way it does for reasons that concern beyond just yourself. When you propose a change, think less about making the game into precisely what you want it to be and think more about what makes a good, competitive game that's also spectator friendly. Think about how it can be improved and think about a compromise more than trying to wipe it off the face of the game and above all else, when you make suggestions, be clear, concise, objective and respectful.