My 4.8 year old son can dress and undress himself - although he only has to pull up his trousers (he wouldn't be able to manage trouser buttons, as his grip is not strong enough to pull the material together and deal with the button) and I don't expect him to tuck his shirt in. I also wouldn't expect him to be able to tie shoelaces, yet. He could do socks and shoes (with velcro) before anything else, then trousers, then t-shirts, then pants, and last of all shirts and coats. He can only do that at this age because I literally taught him how to do it (and he's practised it): how to work out which way round things go, how to lay them out, how to do buttons and zips, how to get things the right way round again if they end up inside out, how to get your jumper off without the t-shirt getting caught inside and coming off with it etc. When you think about it, dressing skills are not as simple as they first appear.
I do think it was worth teaching him, as he has low tone and hypermobility, so the pulling on clothes, pulling up zips etc, was good for building up the strength of his grip. I think it also helps with his confidence at school, which was the main reason I taught him rather than leaving him to his own devices, as I was keen for him to be as independent as possible so that his physical differences should not be too noticeable to other children. Maybe a bit paranoid, but he was always so lacking in physical confidence until he started school and is now brimming with confidence in his own abilities, so I feel I did do the right thing for him, as he can see something he can do physically that not all children his age can (rather than noticing that other children can hop, run fast, climb stairs normally, colour in drawings without finding it exhausting, etc).
I think it might be worth trying to persuade your son to be a bit more independent with his dressing, now he's 5 - maybe start with getting him to do his own trousers each morning and work up from there? Or make a game out of learning how to get dressed? My younger son loves having his clothes laid out in a circle around him, he then jumps on all his clothes and chooses what to put on first (provided it's logical to put that particular thing on first.... wouldn't want him going out looking like Superman...).