Actually, it can (and often does) have exactly the opposite effect. Just "working on your (swim) fitness" alone readily reinforces bad technique, as you will be repeatedly practicing (1000s and 1000s of times) incorrect and inefficient movement.
To make another parallel, I see this all the time on the driving range. Guys with gawd-awful horrific swings that are just beating the ground into submission. They make no changes to their swings, no attempts to "fix" their flaws and are basically trying to make their awful swing work for them by forcing themselves to work around their problems (which is horribly unreliable).
Guys just beating a bucket of balls on the range are looking to have their volume (i.e. fitness) replace their technique. It usually doesn't work because they are ingraining very poor mechanics.
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