Very true. Introductions can be “signal” or “noise”. Founders definitely should curate those intros and be willing to say NO when appropriate, but I think the earlier step for the founder is to establish their own networking goals. They need to specify what kind of connections they are looking for and then communicate it clearly to those who can help them. Many people just haven’t thought this out, so when they’re offered the intro, they have no standard for accepting or passing on it.
As regards double-opt-in intros, my startup actually streamlined that process considerably as just one of the features of the LincSphere networking productivity app.