Cornix-- the problem is reaction requires carry thru, ie momentum to work. WHen you react to a certain thing happening you are assuming that the move will continue to carry thru enough to earn profits above your commission.
Predicting, on the other hand, enables the trader to enter a trade prior to the "reacting catalyst" therefore the ability to catch 100% of the move if it occurs.
Reacting is far too slow in today's markets-- as the move is often over by the time one reacts to it.
I must admit indeed that reaction works much better in thinner and more volatile markets, while liquid markets like EURUSD or ES are much harder to momentum trade intra-day except rare times when some serious news shift them into "runaway mode" as well, aka 2008-9 like action (ideally). Subjective, but such is my experience.