Ironically, I think the people responding to and freaking out about your response proves the OPs point, that many engineers treat PRs as an exercise in ego stroking rather than reinforcing software design.
When I was a junior engineer, nothing annoyed me more than engineers trying to 'teach' during code reviews and doing so in one of two ways:
1. Being vague and unhelpful under the guise of having me 'figure it out'. They would point to a spot and say 'This needs fixing, rework this', without saying how to rework it other than to figure it out. Eventually I would need to drag them into a call to get them to tell me how they personally wanted it fixed up. Often times the way they wanted it fixed was incorrect because they misunderstood the work or were just wrong.
2. Giving incredibly bad 'improvements' to the code. Things like 'change X loop style to Y loop style' where Y doesn't affect the readability or performance of the code, or things just for the sake of adding comments.
So nowadays when I do PRs for juniors and such I try to have direct, actionable comments with rationale and room for disagreement, or if something needs to be reworked I try to assess why they did it that way and do a quick call/discussion with them. Junior engineers are generally not dumb and too many seniors treat them as such.