I honestly think that there are non-swimming, and very poor swimmers who have scuba certification. I was certified eventhough I was able to only swim on my back, did about 4 strokes with the crawl, and can not breath well with any strokes (except the back and side stroke). Now, many shops routinely only test the swim skill with mask, snorkel, and fins. Even naui require only demonstrating like only 17 strokes with forward progress, I understand, as the minimum.
Since then, I've learned to swim well. I am more comfortable in the water, even in rough sea, high waves, and current. I think you'll feel alot safer as a scuba diver if you mastered rhythmic breathing with either the crawl or the breast strokes. It prepares you for an out of air situation where you can't count on your snorkel or regulater, and being pounded by waves. It will keep you from having a panic attack or anxiety attack on the surface if your BC is not inflating, or for other emergencies.
If you love scuba diving enough, I am sure you can pass the snorkel/fin challenge, and the treading water ... without really being comfortable at swimming. But I would encourage taking classes, or working on your own, at mastering rhythmic breathing with either the crawl or the breast stroke.