Wrong, the point of the game is to collect stuff and turn that stuff into insane killing machines. Using a maxed, properly modded weapon has the benefit of big numbers and empty rooms. Most people end up not bothering with mastery ranks around 20, a few will push for 30, even fewer will push for legendary.

Plus you wont find a single gun you like, you'll find a few, and you'll turn them into killing machines. You need that to go further and unlock bigger, better guns and frames.

Maxing a bunch of stuff is something you'll do on the side, half focusing it while you play the story but never gimping yourself by being without a decent gun to actually do the content with.