TL/DR: A transaction fee market exists without a block size limit assuming miners act rationally.
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Miners being net econo-rational is probably an axiom for Bitcoin to work in the first place.
This is the biggest assumption of various schools of economics. However, economy is always political, economy policy is decided by the ruling class to manage the majority of poor people, so they are modeled towards average households that barely can live without the next pay check. For these people, econo-rational means short term profit seeking
However, the definition of econo-rational is different for different people, depends on their income, their time frame, and their risk tolerance level. If you move those theory to bankers and large capitalists, you will clearly see their behavior do not follow these models. As we know, the miners and pool owners are bankers and capitalists in bitcoin ecosystem, so they won't seek short term profit like average household, their concerns are much larger and longer term