We cannot rely on there always being some minimal number of transactions to be included into a block except for the coinbase transaction. While requiring a minimal number of transactions would solve several issues, I don't think that should be done as we need to consider the scenario where few transactions are being made. The network would grind to a halt if for some reason transactions are not being made (could be from Bitcoin falling out of use and becoming an even more niche thing, some layer 2 solution makes onchain transactions few and far between, some vulnerability is discovered that people stop making txs but the blockchain must go on, etc.).
I just realized that it doesn't make sense for the network to grind to a halt. Assuming that a miner has even 1 satoshi, they can construct an infinite set of transactions between their accounts on the same block. However, there would be less incentive to do this as opposed to accepting transactions from the network due to transaction fees.
I do agree with you on the fact that the hashing algorithm is the thing that determines ASIC resistance though.