Any decent TA book (I'm thinking of Murphy...) will say that no one technical pattern/indicator should be used in isolation. in fact, from what i've read, confirmation with other TA indicators/patterns is one of the basic ideas of TA itself. Most say that good TA begins with a basic understanding of determining trend from observing price action (HH,HL,LH,LL etc etc), especially the trend of timeframes higher than the one from which you take your entries/exits off.
From there, you add other forms of TA, such as S&R, Fibs, Pivots, Oscillators etc etc to build a strategy which, when combining a few of these "indicators" together, ends up providing the components of a set-up which should have higher probability of success than if you used any one of them in isolation.
Even Nison et al say that candlesticks are simply another ingredient to add to a trading strategy mix - they're good for helping determine bullish, bearish, indecisive price behaviour, but no use at all for indicating how far prices will reverse/continue.
People tend to want to look for a set rule - ie, "always sell divergence of RSI with price", so they don't have to think and interpret the current market, when i think that even the guy that invented RSI would never use it in isolation like that.
If you are looking at RSI divergence, combined with (say) a pivot, and some bearish candlesticks, in the direction of a higher time-frame trend - that could be a good high prob set-up, where as selling RSI divergence alone in the face of a raging price action trend has a very high likelihood of failing (take it from someone who knows!)