So how do we define momentum? If we have to define momentum, even for ourselves, how do we do that? There has to be some criteria, some quantitative definition, even just for ourselves. And if such quantitative systems are created, many do back tests for these systems. TA can be added as another layer to these systems, we can reject or allocate more based on the charts, this is discretion, but it can help. I personally don’t buy at ATHs, because I have no fundamental knowledge of these companies, so I don’t know if price can go above or not, my TA understanding cannot help here.
We do what works for us, and if we are making profit, and even if we cannot explain lucidly about our process, but if we are doing it for a while, and are in profits, and if we are reasonably confident that we can continue doing it for extended periods, I guess then all is good, and this can be called as an edge too. And all of this evolves with time, as we gain new knowledge, understanding and modifications, also creating new things.
Just like investing, this is a journey too, but unlike investing which is called as boring by some, this is very exciting, so there is that 
And I am sure you cannot deny this thread, go through it again, even if you have read it before, you will definitely gain many insights, if you want to experiment or try.