> If your webmail client does that, it's time to switch to a better one.

Academic users constitute an audience that's quite often bound to use a single, potentially-outdated webmail system. In our experience, academic/University users are utilizing what we consider "nonstandard" email systems with an order of magnitude more regularity than nonacademic users. You may wish to better understand the audience of the product before asserting that they should "switch".

And claiming something is not a security issue because you're trusting a client you don't control to behave well is naive at best, and apologist at worst. It's genuinely upsetting to hear coming from someone who classifies vulnerabilities.