Whilst some airline rules may seem curious/strange, you can always decided not to use that airline.
Ah, that old chestnut.
My company decides I need to go on-site in Chicago for two weeks for a project. The secretary hands me my United booking reference. No choice was given. I never agreed to the airline T&Cs.
A family books an inclusive-tour holiday. On the day of departure it turns-out it's on a Volotea 717 and only the first 75 passengers are guaranteed cabin baggage. No choice was given. They never agreed to the airline T&Cs.
Both actual events. Names removed for witness protection!