To totally wing it is a good skill...but you need to know who is capable of doing that.
If these guys have supreme confidence that they can do this..and you know that, and they know your level..then for a bar gig, then should be fine. (thinking and doing though are not always the same)
However, they picked a random singer at your audition... and there were 2 red flags there...he was rubbish by your criteria, plus a total lack of planning.
You turned them down...meaning they didn't impress.
One of things that defines your stature in this field is what gigs you will not be involved in. And yep, those players that need to know that stuff, definitely notice it.
For want of a better way of putting it, if you are trying to be a tier 1 player, playing in a tier 3 band...you will struggle to get tier 1 gigs. This is why it counts against you ime.