Notes from the December, 2016 teleconference:

The problem is that overload resolution relies on copy initalization and thus does not describe direct initialization. See also issue 1781.

The term “implicit conversion sequence” is now used in some non-call contexts (e.g., 7.6.1.9 [expr.static.cast] paragraph 4, 7.6.16 [expr.cond] paragraph 4, 7.6.10 [expr.eq] paragraph 4) ) and it is not clear that the current definition is suited for these additional uses. In particular, passing an argument in a function call is always copy-initialization, but some of these contexts require consideration of direct-initialization.