I thought technical analysis (as opposed to fundamental analysis) assumes markets aren't efficient and subject to things like herd behavior and other psychological effects of human decision making. Otherwise things like momentum trading wouldn't work (i.e. price would just gap to the true value if markets were indeed efficient). If tech analysis works at times for me it would show that markets aren't that efficient as a whole.

IMO markets can't be efficient because we as humans aren't - our perception of value itself can be subjective and influenced by many things including FOMO, safety in numbers perceptions, risk aversion (usually), etc etc.