in kaifuku jutsushi, it's a different case
they acknowledge that the healer is important
so important that they choose to turn him into a mindless tool so he can't ask rewards fitting for his usefulness
in this manga, they are simply looking down on healers without even bothering to consider their role in battle.
even though there's a living example of how ridiculous a well-trained healer can do
it's illogical to say the least, and idiotic to be blunt