i think when parents say that their children are too young to
understand wad love is, they actually mean "they are too young to
understand how loving someone is like when you are an adult (which
you will be for most parts of your life)".
as a person matures in his life course, he will start to want
different things in a partner. and it is only his "adult" version
of this "want" that will see him through to marriage and a
life-long relationship. so before he reaches this stage in life,
his priorities in choosing a partner may be utter bullsht and
parents feel that this is like "wasting" his studying time in
"trial and error-ing" with r/s, since ultimately, he will end up
with a different set of ideals when he is finally ready to get
married.
i hope i am making sense here...
the second issue is the distracting factor. although it is true
that well adjusted individuals can balance different aspects of
their lives, it is also true that when relationships are affected,
their moods, behaviours, studies are affected. their priorities
change to focus on r/s instead of studies. and to a parent, young
love is not something that can be taken for granted to last. hence,
they will prefer their child to "concentrate on their studies" to
having a relationship anytime.