The tightness required to give a secure electrical connection is not the same tightness as
required to hold the weight of a connector and a couple of yards of 4sqmm 2-core cable.
Just by itself that'd be bad enough, but a jack cable compounds by making the sleeve
connection a fulcrum to provide an inch or so of leverage to the tip connection. Hence
the joy of regularly having to lever the tip connection back out again on a guitar
Sure, DINs weren't any damn good either, but even they didn't have the
leverage problem that jacks do.
And my experience is that if you trip over a
guitar cable, it'll pull the whole rack onto the floor *and* then come out of the socket
as well. Maybe I'm just lucky that way.