[teddyh]

ISTR a discussion in Tog on Interface on the design choices available, with visual examples. This seems to indicate that the choice was made there.

[RodgerTheGreat]

You're thinking of a discussion about a hypothetical variant of the radio button, a "one or more" UI element. Discussion here on Lobste.rs:

https://lobste.rs/s/v6mkz6/implementing_one_more_ui_componen...