See this is a straw man too...
“what if I was useing a class feature toy help that stopped me from healing you”
is not anywhere near the same as
“What If on my turn when I can heal you I choose not to”
now if every now and then we disagree on weather you should have healed last turn or not (unless I die because of it) no harm no fowl. BUT if every time I call for healing, you choose to withhold it, and you do so because you don’t want to use your spell you preped and you and I both know it... that is going to be some sore feelings.
The class feature they are using that stops them from healing you includes "cast a spell" (that isn't healing you) and "make an attack" and "prepare spells that don't include healing spells".
The build choice they made was "not play a life cleric", so healing spells are much less efficient and almost always worse than trying to take the damage dealing foe out.
If "every time you order someone to do what you want", they never follow your orders, the problem might not be them.
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Note that you can buy healing potions, burn your action and regain an average of 7 HP, greater for 14 HP, superior for 28 and supreme for 35.
A healing potion is similiar to a 1st level cure wounds, a greater to a 3rd, a superior to a 7th level cure wounds, and a supreme to a 9th level cure wounds (not that anyone would use a 7-9th level slot on a cure wounds).
If you are playing a game where potions are a bonus action (which I hear is common), then drinking that greater healing potion is easier for you than the cleric using a 4th level healing word (as your main action isn't constrained; casting healing word on a cleric prevents your main action from being a spell with a level).
Using a bonus action on a 2nd/4th/9th level healing word is a mediocre to poor use of a slot and a bonus action. When I have healing word and this is a one-fight day where I don't have a spell to cast, sometimes I'll burn 1st level slots on topping up a wounded companion critter or the like.
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Demanding someone heal you in 5e is like being in a boat with a huge hole in the side, water pouring in. There is one guy operating a non-waterproof radio in the still dry part of the boat to send out an SOS signal, and you are yelling at them to bail water instead.
Then you blame them when someone drowns before the rescue helicopter arrives, ignoring the fact that the SOS was by far the most important thing to be doing, and bailing water when you cannot even close to keep up with the inflow is not very useful.