2 different things, that's why.
What do you mean "that is why" ? I was buying cryptos for the past year using those cards...
Your credit card issuer doesn't care about charges for hosting fees, SSL, or Fiverr -- those may be crypto-related
to you, but they aren't to your bank. Your bank just sees them as web services, freelancing, etc.
When they see you charging credit to buy bitcoins through Simplex, that's a
very different type of activity, which is prohibited by the bank.