I'm not sure what makes people feel it is all that revolutionary. I mean, 4e has action types, PF2e has action COSTS, its not all that much different. I think the PF2e approach might sometimes give you slightly more complicated choices. So, like in 4e if you have a minor action effect, there's no question, you can do it or not, but normally it won't be a choice between that and making some bigger splashier main attack, whereas in PF2e that might be an option (IE make a 3 action attack or a 2 action attack and something else that takes one action). Is that a GOOD thing? I mean, it eliminates the concept of action types (at least for in-turn actions, PF2e still has free actions and off-turn actions) but replaces it with "action cost" instead.And I cannot speak to your friend, but the 3-Action system is a revelation. It's one of the absolutely best changes I've seen in a d20 game, because it eliminates so much of the nonsense around the Action Pyramid. If they got nothing out of it... well, I don't know. Maybe they were just going for a "3-Attack Round" every time. I don't know. For me, I've found it to be really cool, delivering relatively fast combat with lots of resolution and tactics while still feeling close to something like traditional D&D.
I'll just close by saying that in HoML I did away with the minor action. It was always too tempting to design in extra attacks and such. If something is really trivial its a free action anyway, and if it isn't, then its a standard! Likewise with bonuses, HoML has ONE situational adjustment, advantage/disadvantage, and that is it. There are fixed bonuses from 4 sources (level, proficiency, permanent, and ability), and they NEVER STACK. You just take the best one you have, and they don't change, unless the character itself changes. Things run WAY quicker this way! People don't worry about little stuff, they go for the tactical 'breakers', the things that give advantage! My game design motto is to not sweat the little stuff, if something isn't "oh WOW!" then its just taking up space and should go away .