That's neither fully correct, not universal. The medieval ages had a lot of traders with very little land and a lot of coin be very important. The Hanseatic League and the Italian trade cities for example had little land and no titles, but still wielded enourmous influence due to their wealth. Aside of that, many nobles and even some Monarchs had to regularily kow tow to rich traders and burghers because they needed their money to finance armies.
For history of medieval Poland, Germany, Prussia, Pomerania, Czechia and many many more, most wars have a bit that goes "and when the king has everything planned out, city A B and Z said "nah, we're good"" Breslau, Stettin, Cracov, Prague and Danzig were particularly repeat offenders, if they joined a war **** was getting real. As Niomedes mentioned, these are all either Hanzeatic or Bishop cities, thus financially independant.
The Teuton order was entirely dependant on coin. Good thing for them, so was Sigismund Luxembourg (known as the baddie from Kingdom Come) who ie took 300k guldens for striking Poland from south when war broke out. What war? Contination of the war everyone knew would re-start when Wencislav IV of Prague (and also KCD fame) took 60k guldens from Teutons for arbitraging the peace in their favour, which everyone expected would lead to war.
Then, in battle of Grunwald/Tannenberg in 1410, infantry got to knights first, and only ~300 hospitalers got out alive (typically, even people who eventually died because of the battle, got out, if wounded and with x days to live). But the costs of their ransoms were such a burden on the teutonic knights, that it crippled their ability to challenge borders and raid across them for decades to come.
To defend OP, he has a point, and it is reflected in early-game mechanics.
Look at how well Templars would fit here.
Templars operated a simple scheme: they'd get donated lands in Europe someone didn't want, usually, because that land was not controlled by them in the first place. Robber barons were both real, and sometimes made up by their enemies (raubritters on castle Książ can act as a good study of how hard it was to tell). Sometimes ownership was contested between to regular knights, many famous knights ie Zawisza the Black started out with rights to half a castle. Here's the kicker though: if you donated land to a church organization, and templars were technically monks (their ruleset was just copy-paste of Cistercians, order formed by nephew of one of founders of Templar), Vatican issued a papal bulla. A special document listing A as original owner who donates the land, so if the order were to be (cough spoileralert cough) disbanded, that family would have a much stronger and most recent claim on that land.
But the reason Templars story ends as it does is because king of France was desperate for coin to mess with Vatican. And got away with nothing, because Templars weren't hoarding the coin, they were blowing it all an continuous flow of fully equipped and trained knights ready to patrol and skirmish in Middle East. By which time they were both bringing Arabian knowledge back to Europe , as well as reintroducing Greek works on mathematics, medicine - as they only survived in Alexandria at a certain point. So that bakfired terribly for them personally. If you don't know specifics, typically 1-3 local commandorie leaders were executed, and most joined other orders or downsized to monks as beside the combat training, they were already basically Cistercians.
But yeah, coin was a BIG dealbreaker at times in Europe. Other times, yeah, Augsburgs in XVI century one time spent iirc 60k guldens, legit a war-worth on a horse and rider armour that they then promptly misplaced (lost a ship, should've spent some more on corsairs I guess). It can be seen in Dresden museum, as a proof that yeah, at times it was not a limiting factor at all.