Re: How to avoid getting blocked on neteller/paypal/skrill/etc?

Don't act like a red alarm, be quiet just like regular user. Personally I have never had problem with skrill: https://www.skrill.com/transfer-money/skrill-cryptocurrency/

Don't they prevent you from withdrawing your coins if you buy or deposit it with them?

That's correct[1]. You are only allowed to sell the coins back to them. I don't see any reason to use their crypto services.

[1] https://www.reddit.com/r/CryptoCurrency/comments/azv5pz/do_not_use_skrillcom_for_exchanging_bitcoin_they/