Baron Von MunchKrausen said:
I question the value of it.
Skipping Irish Moss doesn't hurt anything.
When the outcome of the beer is acceptable, IM isn't needed. IM doesn't create hot or cold break, all it does is create a charged surface area for the break to adhere to and settle more quickly and completely.
The test is with chill haze. The more you have of it that won't settle with reasonable time (a week or so), the more you'll benefit from IM. Stone Brewing went through several months of slightly hazy IPA that was caused by an unintentional reduction in the amount of IM used.
Most of the time, chill haze is related to tannins and cold break. Part of the creation of cold break is how fast the wort can be chilled. The faster wort can be chilled to >70 F (20C), the more effective cold break is, resulting in clearer beer.
So, with a vigorous boil, whirlpool and swift chill, IM can be reduced or eliminated if the brewer thinks the results are acceptable.