Sure on paper they are different things and they both involve different parties but in practice both are accepted everywhere. I never had a credit card but I have been using debit cards for decades and only twice an actual credit card was required: for booking a hotel abroad and for renting a car abroad.

They point is that they probably also accepted debit cards, not just credit cards.

The only places I've found that only accept credit cards are hotels.

In 99% of the places I can use my credit card I can also use my debit card, online or offline (well, except in Germany with their EC cards and stuff) that's the relevance of my point...