Volvie, with all due respect to you (and I do respect your hashkafa, I am not being sarcastic), I could not disagree with you more. Ehrliche frum girls in the decades of the 50s through the 90s met their zivugim in this way, and it led not to indeceny, but to marriage. Yes, there will always R”L be people who behave inappropriately, and by that I mean indecently. The fact that ‘some” people might be nichshal dos not mean we throw the baby out with the bathwater.
Many, many shidduchim were made b’tznius and with the most honorable of intentions, through people meeting at Shul youth groups, Bnei Akiva, informal gatherings, etc. And btw, you don’t “allow” girls to give their numbers to someone whom they have met in a wholesome environment. If they are old enough to be ready for marriage, they are old enough to give a guy their number without needing special permission. That being said, if in your particular circles it is not ever done that way, then by all means keep to the status quo, and may all the single girls and fellows find their proper zivugim ASAP.