What really stops attacks is killing or completely incapacitating the enemy. Anything that doesn't involve that increases potential damage to you.
If you have a team with 4 or 5 PC's then stopping your attacks to be more defensive doesn't stop the enemies from being killed as the rest of your party can potentially attack and kill them.
The thread is about melee vs range and mostly about martial pcs, their actions are better spent making all their attacks on the enemy to get their damage across.
Simply not true.
You are a melee PC (definition of the thread) so you need to get what you do (damage in most cases) over as fast as possible. Its more efficient to trade HP (a resource that is easily replenished) then use an action to possibly avoid being hit.
This also is untrue. You are not factoring in teammates. I'm not saying you should always dodge. But it definitely should have a much larger role than you envision.
Dodge would only have use for a martial melee PC if it would be assured to lead to more damage the next round then this round and the next round combined otherwise its the same damage just a round later.
Having allies mean that when you dodge the enemies are still being damaged.
To me its only of use to avoid a certain death, then it has value if you would be down and then not revived the next round to act again.
That's because you highly undervalue it.
There are few situations that it would be useful, if its for free or a bonus action, like a monk for example. But to trade all your attacks for possibly avoiding an enemies attack to save HP is way to high of a price to pay unless it would lead to immediate PC death. If you are a martial PC its would be better to nova as much as possible before you go down and then count on your party.
Dodging doesn't necessarily compete with NOVA rounds and even then there are plenty of situations when dodging the first round when there are many more enemies capable of attacking you than using your NOVA abilities.
You also have the problem that intelligent creatures run by an intelligent DM will stop attacking a creature that is harder to hit and no threat (you are not attacking) and move to attack another PC.
I always assume the DM will play enemies (at least the ones that ought to be intelligent) somewhat intelligently. Why would you think I don't assume that? I also assume that the DM doesn't metagame my enemies. Do you make that assumption too?
So to me that means when I use the dodge action the enemies don't really know that's what I'm doing until they try to attack me. After the first attacks me they may learn if they are all intelligent and communicating enough. If not the enemies may very well still attack me as they don't immediately know that's what I'm doing.
If you are in these situations then your HP management is a problem or you have the way bigger problems of a potential TPK. Dodging then just delays the inevitable.
Again that's absolutely not true. Dodging is useful
1. It can force damage to be spread around after being moderately wounded. This also has the added effect that enemies that refocus on other allies may be less likely to focus back on you even after you start acting again.
2. In many situations it's as useful of a combat initiator as a NOVA.
3. It's an amazing tool to have in holding a choke point
Frankly all of your arguments against it sound like they assume you have no allies.
This could also be a difference in game styles. If you know your DM will just have all the enemies keep attacking the dodging PC this turn and leave everyone else alone, then dodge has a greater value.
And in normal games where enemies learn a bit as the fight goes.
I have seen it used maybe 4-5 times from a non-monk, non-rogue PC. Those types then usually take Mobile feat as it makes for greater action economy.
Then your in no place to say how useful it actually is. You have nearly no experience with it and there's no evidence that you have even attempted to analyze it in respect to a party success as opposed to individual contributions.
