...need to be ended.
They represent a huge risk for bias dependent on the personal characteristics of the investigators to rule the day.
Are you an older, white-haired, heteronormative appearanced, able-bodied picture of "Scientist and Professor"? Great!
Are you overweight? Do you stutter? Express unexpected gender presentation? Nonwhite? Female? Are your language skills less than native to the reviewer's ears? Too young? Too hot? Not hawt enough? .... Not so great.
Should your grant proposal be affected strongly by the direct face to face impression of these characteristics?
Update: See PDF for site visit procedures