They knew this was coming and did nothing about it.

[lezard21]

The "indie company didn't expect huge player explosion" excuse really doesn't work.

Square Enix sold the expansion and charged the monthly fees. Square Enix had the sales number and should have realised that the number greatly exceeded their outdated servers' capacity. Those sales did not happen the morning before EW launch.

Saying a week earlier "oh btw, too many people might have bought the game so expect congestion, woops" after you've already purchased the expansion and paid your monthly fee is not a warning.

Square Enix should have refunded Endwalker and monthly fee to everyone along with a disclaimer stating that the amount of players intending to play the expansion was way beyond their outdated server capacity.

Then, and only then, if people still bought the expansion and faced the congestion would they have had no right to complain.

But that's not what happened at all.

Square took our money and now people are not getting access to the service they paid believing they would be able to.

So people have a right to complain and demand compensation.