I spent most of my professional life working in various roles in aviation, which included several years in a customer facing position at an airport.

I'd recommend never ever using reseller agents. They frequently mess up tickets, they sell tickets that don't exist at all, and most of them won't forward your contact info to the airline's system, so if there's a problem or delay you'll never receive the notification from the airline. (Including coupons, hotel room offers in case of cancellation and other stuff)

The airlines may be bad but the resellers are worse.

The biggest problem, IMO, is that if you buy from a third party when shit hits the fan you have to rely on that third party. This is still a problem even with reputable travel agents like Amex and Chase. Even in the best case scenario where the agent is actually good, having to get a flight changed via a phone call with some agent who might or might not answer promptly and might or might not be able to work quick enough to win a race of rebooking after a cancelled flight before next best one fills up is just asking for a horrible experience. If you book with the airline directly they have a lot more leeway and power to unfuck your situation promptly.

Save your points and use them on hotels instead, where the experience is just as risky, but at least fails in a less spectacular way when it goes wrong e.g. unless you're booking with an agent in a high demand area where there are NO hotels you usually can leverage a backup plan a lot easier than if you are stuck in an airport.

Yeah, after all these dumb dark patterns of low price on the price comparison site and a different price after passing all the stupid lies and upsell attempts of the reseller websites, I nowadays book with the airlines directly.

I've had similar bad experiences with hotel resellers. You book a hotel with Expedia and roll into a foreign town at 11 pm after changing a flat tire on the way and the hotel says "we never heard of you and we are full."

I've never been stranded when I've contacted the hotel directly, via their website or the phone. Sometimes a glitch does happen, but when it does the hotel will call around on your behalf and find you a room.