sideway market is predictable and it will move as per exact technical things. If you are good in technical skills then you can easily make use of sideways market for short term trading to make quick profits.
Probably sideways market is complete unusual for crypto traders as they are used to enjoy either strong bullish or bearish markets at most part of their crypto trading life. It means when they need to encounter something new and unusual, they find difficulties to tackle market directions which could a reason for people like OP to blame technical analysis rather than improving themselves suitable for market conditions for easy profits.