I am not sure that I agree. I am open to discussion though.
I am a non-fighter (mainly because of time involved to fight manually and the incredible inability to win early on). I had read that auto-fight was basically useless so manual fighting was the way to go, if fighting was chosen. I know that it used to be, and still remains very expensive to cater, from a resource point of view. But, it is simply easier for me to cater, so that is the choice I made (over two years ago). Because of that, I have specifically built my city accordingly over the passing years (minimizing military structures, maximizing goods production, and investing is Ancient Wonders that continue those themes). I also had absolutely no interest (or incentive) to invest valuable KPs into tech that was not going to be used by me and was explicitly designed to be optional.
Since I do not fight, I really have no experience, but I have ready the various threads posted on the forums. If I remember correctly, after the devs "re-balanced" fighting for either provinces or tournaments became easier and the other may have become more difficult (depending on chapter, I am sure). There are multiple arguments whether this was a true balancing or not. However, I would personally feel that a retroactive decision to force squad size research would be very unfair to those of us that chose the more expensive path of catering (and invested time, planning, and resorces accordingly).
This game is all about choices (differing modes of play, different balancing of population, culture, production structures, different uses of space, different participation (or lack of participation) in tournaments, events, trades, etc.).
Bottom line: there are advantages to military strategies and advantages to non-military ones. Catering costs more, but there is no need to invest in military research/structures/etc. Military requires more research, but you don't have to spend the resources to cater. That seems like a certain form of balance and fairness.
All of this is just my humble opinion.