This seems like an unfair representation. In a game that has always touted "make it your own" and 5e constantly boasting rulings over rules, it's perfectly fine for GMs to interpret and tweak rules to suit their image. We're not even talking major house rules here.
Actually we are, some people must have combat be only an abstract minigame because they want it so much to model reality that it breaks down the model, to the point where they need to have combattants whose turn it's not freeze into place, which means that they are completely confused about the length of a round: is it 6 seconds or is it six seconds per turn, meaning that in a fight with 10 combattants, a round is one minute long with people being "frozen" 90% of the time.
This is not at all the way the system has been designed, from the very first editions to 5e. No explanations where provided before AD&D, but these were very clear, although the round was much longer at the time (which is really unrealistic as well, by the way, anyone having done some fighting knows that it's impossible for bouts to last that long): "During the course of one minute of such competition there are numerous attacks which are unsuccessful, feints, maneuvering, and so forth. During a one-minute melee round many attacks are made, but some are mere feints, while some are blocked or parried. [...] So while a round of combat is not a continuous series of attacks, it is neither just a single blow and counter-blow affair. The opponents spar and move, seeking the opportunity to engage when an opening in the enemy’s guard presents itself."
This is echoed in 5e: "In combat, characters and monsters are in constant motion, often using movement and position to gain the upper hand." So basically, thinking that characters freeze stupidly in mid-air to support an abstract completely sequential activity is totally opposed to the design of the game, and causes havok and many further inconsistencies with things like durations (spells now have durations that depend on the number of participants in the fight, how silly is that ?).
While there are some sequences in the resolution, most of the fights across the field are independent, for once, and second the system never says how long it takes to perform any action for a given character. In one round, making an attack might take all 6 seconds because of circumstances whereas it might be done in a wink in another round, again just because of circumstances.
Wisely, the game system, who thinks that narration of epic fights is more important than having a combat minigame, leaves a huge amount of flexibility on all these elements, leaving the DM and the players free to weave their narrative over the technical resolution of the actions. It's only people who insist on "realism" and codifying the actions on their own beyond what the system does who end up with contradictions that they cannot resolve. But it does not reflect badly on the system, all these additional constraints are not inherent to the system anyway.