I don’t see that as a complaint and I’m hardly screaming! I’m sharing my perspective and asking for other perspectives. Which is the point of discussion isn’t it?
You did come across initially as very judgemental of people who use e-bikes - especially those who appear , to your eyes, anyway, to be 'fit and strong' - and seemed to be demanding that people have a reason which is acceptable to you, for riding them. Tone is almost impossible to put across on t'interwebz, isn't it?
Let me ask you, would you ever consider asking the same blunt question of people who use wheelchairs? Many wheelchair users 'appear' - on brief or initial acquaintance at least! - to be 'fit and strong'. Many of them are indeed 'fit and strong' as will soon be evinced by the paralympics. Does that mean you think they don't need, or shouldn't use, a wheelchair, or that their use of a wheelchair somehow disappoints you and diminishes them?
Of course you wouldn't, and you don't - yet the impression you put across in your initial post is that you are somehow disappointed that people who you don't think should 'need' to use an e-bike, are doing so nonetheless.
Maybe you could have put it in a less-confrontational way -
'I'm puzzled about e-bikes and their growing popularity. Would those of you who use them, be willing to explain? I'm especially interested to know why a person who considers themself to be fit and strong would ride one. It's not something I've ever considered'.
Or something like that?