I also find the incredibly vague and nonspecific "but security!" scaremongering language to be quite hyperbolic, a repeat of the borderline lies mozilla peddled when they decided to dump xul for webextensions.
It seems to me that the removal of features like this amounts to "I don't use/understand it, therefore I'm going to assume it's not useful to anybody".
Of course, Mozilla being out of touch with its user base is hardly news, so this comes as no surprise at all to me.
(While I'm talking about browsers and particularly mozilla, I'd just like to take a moment to congratulate them on finally getting their market share down below that of edge. They've been working hard at driving firefox into the ground for a long time now, and I'm sure they must be feeling very proud to have finally achieved this important milestone in their seemingly unending quest to achieve that holy grail of 0 users. So I'd just like to say: Nice work, Mozilla!)