When BTC is up all other coin move up. So why spending time on doing technical analysis on alts when doing it on BTC gives you a potential clue of most assets price direction?
This is not always the case. Sometimes the upward movement of bitcoin doesn't measure up with the same percentage for other altcoins and I don't see that as something that I should always depend on because not all altcoins will obey that move especially if the coin is a new project and has not gotten that kind of popularity that is expected. But top coins like BnB or Ethereum usually follow same move made by bitcoin. But to do a TA on low level altcoins might be confusing because they are easily manipulated and that will go against analysis made on it. So it is better to follow sentiment on it.