From what I understand, that's 50,000 pre-generated transactions pumped directly to the mining node. Not 50,000 transactions spread across hundreds of non-mining nodes and relayed to the mining node. There's a huge difference. Correct me if I'm wrong here.

Either way, bitcoin the protocol can handle waaaaaay more transactions than the BTC devs have constrained it to.

Yes, more-or-less, but that how it is designed to work. The most reliable way to get a transaction into a block is to send it directly to a miner or set of miners. Apps on BSV do this today via MAPI REST endpoints, similar to how this test was configured. Non-mining nodes will see the transactions later, but they won't do the same verification that mining nodes require because they are not part of consensus. BSV generally sees the eventual network configuration as a small-world network for the mining core, and a mandala network for the apps and services surrounding it, rather than as a mesh network which most blockchain systems strive to be.