YmayNBU for your child, but not all 5 year olds are the same.
Agree with previous posters who say you look at your own child and do whats right for them. There will always be parents who think organised activies are no good and others who say they are great.
ds (6) was very tired at the end of the school day at the start of P1, but suddenly adjusted to it by about Xmas. We started him in his first club around January (he has Feb birthday so he was nearly 6 by then).
Its easy for us as ds is an only child and we are lucky he has had teachers in P1 and now P2 who don't give more than 5 mins homework once a week.
The clubs are also 2 mins away, at very convenient times & quite short so no rushing dinner (or is it tea 
) or bedtime -
karate 45 mins (first club he started and its been a great confidence booster for previously very very shy ds)
footie 60 mins (he is a footie addict, this has also been good as they are allowed to play football at playtime in school and again this has boosted his confidence and he actually joins in!)
swimming lesson 20mins (necessary!)
Even though he does "all these clubs" (and another footie and swimming at weekend) he is still very good at entertaining himself.
I am not pushy (I hope!) and don't care what belt he is on at karate, how many goals he scores, or what level he is at swimming - the main thing is he loves them and the 2 x footie and swimming have been at his request.
If (when) he starts getting more homework, struggles at school, shows signs of tiredness, or simply doesnt want to do them we will of course change things as needed, but just now it suits him well. (but costs me a fortune!!!).