This rule is a scam. I have been dispatched under this one time personally. For the hours that are spent teaching new guys this or simply arguing the 20 different opinions people come up , drop the exemption and delay the flight .

I am sure someone will key in and say they get dispatched under it all the time . 5000 hours personally and I rarely rarely rarely rarely see it.

I agree the way Everything Explained for the Professional Pilot does have a great way of sharing his explanation

If destination is below mins in conditional section (TEMPO, BECMG, ETC) 2nd Alternate required regardless of 1st alternate derived minimums: could be severe clear and you would still need a 2nd, because you used 3585 to dispatch. If destination is below 1-2-3 rule, but not below established mins in any section, you only need one alternate and would only require a second alternate if 1st alternate was below derived mins in the conditional section. Why not just use 2nd alternate in that case; most of the time you would. But if you service the 1st Alternate city, but not the 2nd ...then you will likely see both alternates.
NOTE: there are conditional limitations and derived limitations that deal with visibility and/or ceilings that must be considered.

If 3585 is used, the destination weather isn't only low enough to require an alternate, it's also too low to dispatch a flight to under normal circumstances (even with an alternate). You can't dispatch a flight under 121 to a destination unless the weather is forecast to at least meet approach minimums (e.x. 1/2 mile for a typical ILS). If the main body of the TAF calls for 1/4 mile visibility, you couldn't dispatch a flight to that airport even with a suitable alternate. But if that 1/4 mile visibility is only forecast in a conditional part of the TAF (such as TEMPO, BECMG, or PROB) then you can apply 3585 and dispatch the flight provided the soft and hard alternates are added.

Yup, use it several times per winter at a large regional with lots of poor weather.

Oh, and it was "People Express."

Aha!

I didn't know destination weather could be limiting for dispatch, that's what was so confusing to me. Makes sense now. Thanks.