The notion of the software tester as quality gatekeeper is generally seen as outdated; Jason B. Ogayon recently shared We Are Not Gatekeepers that does a great job of laying out the ideal scenario where the product owner is the one who makes the release decision and decides what level of quality is acceptable for the product.
In theory the team shares in the ownership of product quality; this isn’t a hard sell when things are going well. If the product is awesome, the team will generally own that and take pride in the quality, or as Jason noted:
We are not the authority about software quality, because the whole team is responsible for baking the quality into the product at every project phase.
Things get stickier when things aren’t great. If the product has a lot of defects, or is missing functionality that was previously expected, sharing the ownership for those shortcomings is often uncomfortable. It’s easy to blame the tester who raises the issues or reports on the poor quality.
But, much like the whole team being responsible for baking the quality into the product, the whole team, not just the testers, take responsibility for flaws in the quality recipe, and the individual who sets the quality bar assumes that gatekeeper role and responsibility.