I was searching for avaiable PhDs and I saw lots of them that have
"Applications accepted all year round".
What do you think about this? Is it normal? Or is it just a way to attract newbies for their useless PhD?

From what I understand the ones who accept applications all year round are often for PhD positions where you need to provide your own funding.. I could be wrong lol

PhDs can start any time during the year so I wouldn't be put off by it

Tricky is correct, you can apply and start at any time (if they like you and your proposal) but only if you bring funding with you / self-fund. Most Research Council funded PhDs are advertised in the spring and start in the Autumn. Otherwise, you get a handful of outside sponsored PhDs which may start at other times.