No, if there was a rule that prevents removing occupation so u can't siege it again, revolting would be impossible.
The defender can just put the revolt banner between 2 towns and have ganks on both sides making it impossible fighting on the banner. If this would be a rule then also add a feature that allows u to supress siege a vassal.

solution? Don't make it a vassal, if you are worried that they will revolt at any time keep them occupied so you can suppress them.

Also giving only the attackers the ability to place a banner makes sieges boring and unbalanced.
since the attackers will just put their banner in the same place, over and over, because it benefits them.

How else do you expect a vassalized nation to fight back if the ball is never in their court?

This siege was very good example it was almost a lost until the end
Fqrtex is right here as well they wore many time when GNE asked staff to make revolt banner not moveable so it so bias all stuff saying banner should be place where they wanna.
Giving free win just by placing banner where you like , that unfair why people will be bother to try fight like that
attacking siages are hard as they are now making them even harder is not fiar

Then attacking big nations and winning a siege doesn't give you the money back if they don't make them a vassal too

as far as I understand, occupation gives 80% of town upkeep and resources and vassalizing gives 2.5% of upkeep

What actually makes attacking sieges difficult, in regard to banner placement?

I understand the attackers can no longer sit in their invincible fort 'o deepslate and snipe without risk or consequence and that does have an impact, but nations NEED the ability to revolt for themselves without the oppressors being too scared to accept the banner being placed somewhere that is not advantageous for them

It's harder to win, sure.
But if there is no back and forth between a nation it just becomes a chore to do the same thing, over and over again.

Hammering a nation into the ground without a chance of a counter attack nor defender organisation is unfair. If you believe this to be completely fair and reasonable, you have never been put under such conditions.

banner placement is the most important advantage or disadvantage in sieges so yeh its not rly about fort snipers (those will be useless anyway because banner is out of render distance with 8 chunk distance)

Frambaby you clearly don't know how the vassalization/occupation tax system works. I would not be surprised if the coalition is basing false information on their entire argument. I've had over 7 different vassal nations and vassalization is way more beneficial to the owner than to the vassal. Clearly you guys need to understand the system better

I don't want to spoil the surprise for you, but the 2.5% tax is completely different from the 80% of upkeep one

*correction, its 85% of upkeep

Zaify solved this with a different approach