Evolutionary pressures and positive selection does not care for these constructs, getting older isn't likely to decrease attraction to minors in these people
If you want a real answer it's likely mostly because humans only recently became "civilised" as far as our evolutionary past is concerned.
For our entire history before that, it has been evolutionarily advantageous to breed as early as biologically possible.
These genetics still exist and having attraction to minors still haunts humanity. Some studies show very large numbers of adults, in the realm of 10-25% of the population, are attracted to minors. Usually the definition is below the age of consent in the country of the study.
Almost all of these people understand it's wrong and do not pursue these unwanted feelings. When people have overlaps between psychopathy, trauma or other conditions and the attraction to minors they often become offenders.
I think it'd be a shit way to get rid of bodies unless maybe if it was just bones. Fat and soft tissue would probably need a strong base like sodium hydroxide to break down - which is why it's used for making soap
Generating three random bits.. Saved you a click