If the GM needs to "add step 2 point five" in a sequence of step1/step2/step3 to accommodate for common low cost abilities that sounds like tacit admission of those abilities breaking the game's flow in ways the GM is forced to compensate for.
The presented 1-3 is for the exploration pillar, in the exploration section. Combat is simply more involved. It would have been MUCH better if the rules presented a proper combat play loop for DMs to understand the flow. The fact that they don't is one of the problems with the presentation of the rules. Hopefully fixed in the next iteration but I have my doubts.
It wasn't a slight, just an acknowledgement that many started with more recent editions.
I will say 5e, despite it's flaws, is a bastion of clarity compared to any edition but 4e (and maybe 3e, but 3e has its issues and if you don't like how PC empowering 5e is then woo boy).
A reaction like shield or uncanny dodge simply does not work like a save spell. The caster says they need a $type save from the target & the target returns one before the results are given. It's not a case where the caster calls for a save the results are given and the target says no.
This is the Crux of the disagreement.
The results are NOT given, the potential results are given (and only partially, you don't narrate the results of a hit, you say there might be a hit) subject to possible change if the target has something that can change the potential results.
The results are fixed when all actions, reactions, etc. are accounted for then move on. But I'm repeating myself.
Point is yes, if you don't move to step 3 too early, then no issue.
As to my table, I've had players who were particularly disruptive with reactions. If I withhold complete information needed for them to be 100% certain of the outcome before declaring if they pop their reaction ability they get salty & I get clubbed by the social contract for looking adversarial.
Interesting, I haven't seen a player get too salty over the DM enforcing rules (I mean RAW Shield could easily still result in a hit, them's the breaks), then again I play (mostly DM) with friends. But even at Gen Con and a few other Cons players took the DMs rulings and moved on.
If I give them perfect information it slows things to a crawl as every reaction-able interaction is boggled down to a crawl where everyone at the table needs to wait a few seconds for them to weigh their odds or whatever while the GM needs to switch mental gears from narrating or describing to juggling schrodinger's narration.
Again I can see how that would be irritatiting, but I don't play with those kinds of people and they wouldn't last at my table. But also, I simply DON'T move on to description until the actions before it are resolved. That way DOES lie madness.
In the end the way it works out is I look less adversarial & have to deal with fewer frustrated players by just accepting that bob made his PC immune to whatever conditions are required to trigger his reaction, he simply won't be targeted or whatever because I have 5 players and can almost always target someone who is not playing a disruptive meme
Again, this just seems foreign to me. It's not like it's difficult to challenge players who use shield a lot! They tend to realize quickly that perhaps they should have saved the spell slot for later. Counterspell is even worse on that front, it starts eating up high level slots FAST. and I do so enjoy the look on a player's face when they realize they've Counterspelled a cantrip (you don't have time to identify a spell AND counterspell it, that rule from Xanathars I like).