Regarding OTAs, either for airlines or hotels, you generally have two considerations. One is loyalty benefits which a purchaser usually doesn't get when buying a flight or a hotel room from a third-party although there are some limited exceptions. If loyalty benefits aren't important to the purchaser, however, this isn't a consideration.

More important to many purchasers is what happens when things don't work out as planned. That can be anything from missed connections to illness to bad weather. I have known airlines that occasionally treat the OTA-purchased seat just as if bought through their own channels, but most of the time, the frontline folks I've dealt with tell you that your only recourse is through the OTA.

These may or may not be suffcient to dissuade you from buying the fare but should be considered.