Any opinions on roots only watering during flowering?

Does anybody do this, and if so does it have any benefits/drawbacks in your experience? I'm wondering if only watering the roots and maybe a bit of the lower stem could stimulate the upper part of the plant to produce more resin? I think I read somewhere that one of the reasons cannabis produces resin is so that it can keep the seeds in the buds moist and viable during droughts. So if it never gets any water on its buds or leaves or stems won't that cause it to want to conserve as much moisture as it can which would produce more resin to trap moisture for its "seeds" which would equal more sticky icky bomb diggity?