Unfortunately, this seems to be the new normal. And airlines will continue to do it as long as they can keep getting away with it. ... Early March of this year I was traveling to Argentina. Had a flight from DFW to Houston, then Houston to Buenos Aires booked with United. I originally planned to fly direct with American from DFW to EZE, but my Brother had some vouchers with United and (he coming from Denver) all of their flights that fit our schedule left from Houston. It cost me a couple hundred more, but I was willing to spend it to fly with my bro and let him use up vouchers instead of spending more cash.
The day of flight, my leg from DFW to Houston was delayed minutes, then an hour, then hours, then altogether cancelled. United automatically re-booked me with American (on the direct flight I first wanted to use), but this meant I could not meet/fly with my brother, and my upgrade seats were voided. American had no obligation to help me, but found me an effectively matching seat and (with a little sweet talking) gave it to me at no charge.
Coming back, with United again, my flight from Houston to DFW was delayed more hours, then I sat on the runway on board for an extra hour with no explanation by crew whatsoever. I'd have been faster and more convenient to myself by driving from Dallas to Houston and back than going with United. Pretty ridiculous actually.
I've had bad experiences with all the major US companies, but this was easily the most frustrating due to issues both coming and going. United's customer service made no attempt to apologize or offer to make it right. At least they got me there and back.