In the grand scheme of things, pretty small compared to the cost/time of booking a flight and accommodation, but I'm sure some people will probably still forget/miss it.
I've found that actual details on travel required documents can be pretty hard to find. I traveled to Asia last year and the country I was visiting also needed a permit and vaccination stuff. Government webpage no details on the main page, airline had nada (and yes, I checked). I didn't even know about it until I stopped by the airport while dropping somebody else off (same day) and the clerk asked about it. When I googled the exact permit name a government page did come up but I have no fucking clue how you'd even get to that page otherwise if you didn't know what it was called.
Thankfully I was able to take a picture with my phone, submit my OTHER documentation with it online, and got the permit within a few hours in time for my flight.