the answer to your question is pretty simple, that takes you to another question; if you discovered a land full of gold, why would you tell people about it? you would shut your mouth and start digging.

this is the basic human traits.

also regarding most algo trading strategies are built upon obsolete mathematical models, were its alpha has been abused and decayed overtime!

most algos that we see on github are based on what we call TA indicators!

I bet you that more than 90% of the algos on github uses TAlib library in one way or another!

the market is a complex evolving system, most of the algos are pattern oriented!

finding patterns in random data! and this is what we can apophenia.

once you start accepting that the market is random, your google searches will lead you to another field of finance called quant finance, where its essence is modeling this randomness and finding errors or missprices that you can exploit on the short term! and if you are lucky enough your alpha wont decay for 10 years (most of them do decay) you will be the next Jim Simons.

unless you exploited some form of an arbitrage which allows you to exploit the theory of large numbers then you will have a short living alpha (until this arbitrage vanishes).