P0588R0 <https://wg21.link/P0588R0> contains the rationale explaining why
the rules for implicit capture were changed in order to capture some
variables that are not going to be odr-used anyway.

However, it makes the rules too simplistic.

For non-generic lambda, the paper says "Note that we propose applying this
treatment uniformly to both generic and non-generic lambdas (this is not
essential to the proposal, but seems to give a more consistent language
rule)." This consistency is useless. It does ease the workload for some
language-lawyers, but the impact on the average developers is redundant
captures.

For generic lambda, the rules can only apply to expressions in
constexpr-if, and the condition of it depends on a generic lambda parameter.

This is enough to solve the problem to be solved in the paper.