What you describe works fine in theory; the problem is that in practice it's ridiculously easy to overestimate how likely the average user is to train themselves to expect this behavior. In general, we (power users, developers, etc.) tend to adapt to consistent UI behaviours very quickly and to overestimate how difficult it is for an average user, but when it comes to things that are _invisible_ until you do something, the gap is much greater yet.
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What you describe works fine in theory; the problem is that in practice it's ridiculously easy to overestimate how likely the average user is to train themselves to expect this behavior. In general, we (power users, developers, etc.) tend to adapt to consistent UI behaviours very quickly and to overestimate how difficult it is for an average user, but when it comes to things that are _invisible_ until you do something, the gap is much greater yet.