Because, unlike other assets, crypto is heavily volatile.
When dealing in crypto market, we can apply mostly the general statement here that past performance can't guarantee future results. Professional traders are even struggling to make up a good strategy in their respective trading activity and they really did actually end up in several and lots of different combinations of their indicators just to know what would be the best thing to apply.
Crypto has been unpredictable since then. Indicators are a big help. Just don't stop and soon you will hit the right strategy.
but it doesn't really mean that technical analysis is entirely useless. there are many scenario where technical analysis is needed to know the well being of the market, determining whether the market itself is in a good trend or not.
therefore its always combination of both that could helps in trading career, and not depending on speculation.