Should Product Manager prioritize defects?

I have seen many debates on Quora and other related forums regarding how Product Managers should prioritize defects against product requirements. Now my belief is that both are different and I am a firm believer in ‘Engineering owns quality’. Even though quality precedes everything, Product Manager does not pitch defects against product requirements. No product is defect free and every requirement added to the product begets more defects. Product Manager would collaborate with engineering team to determine the tolerance level for the overall open defects or defects open rate. Accordingly, allocate a window in each release for resolving defects avoiding any conflict with product requirements. Ultimately, it is the responsibility of engineering team to prioritize and resolve defects within that window. Engineering team should have complete authority over prioritization of defects and resolve them within the guidelines of quality SLAs (Service Level Agreements) even it is a severity defect affecting customers’ business. Product Manager will be encroaching into their space, if (s)he starts prioritizing defects.

I would definitely loathe if my engineering team is busy fixing defects at the cost of evolving the product. As I had said earlier, both engineering team and Product Manager should agree on the tolerance level for defects, if occasionally the defect rate goes higher because of certain unforeseen reasons, I would urge Product Manager to make more room for resolving defects probably at the expense of not addressing few requirements. However, if it happens too often, then the problem is addressed by identifying the actual root cause. What is causing more defects and what is causing the decline in quality should be ascertained to improve quality in a long run instead of continuing fixing defects at the expense of evolving the product. It is as important to continuously evolve the product as it is to maintain the quality of the product. There cannot be any trade-off between them.