Custom blocks selected by default

Is it a way to set custom blocks selected by default? I mean, blocks that users can deselect in their account settings.

Now it works (only?) the other way round: custom blocks are not selected by default and users willing to activate them can select them in their account settings.

The problem is that many users won't check their account settings nor will play with available blocks, so many features aren't known by non-experienced or non-curious users.

Any idea? Thanks.