Layman here but I believe even a wonderful algorithm requires constant babysitting (as to not accidentally blow up your account via a bug) and the algo may only have an edge for a limited time at which point you need to figure out a new edge for your algo or develop a new one all together which could takes weeks or months. OP has chosen to sell shovels for the gold rush and make some passive income rather than do the constant, back breaking work of digging for gold.

It seems to me that this is a platform for people to build trading algorithms - they're selling that, not a particular algorithm.

I’m sure if someone develops a profitable trading algorithm, the platform owner will use it also.