I've brewed 30+ batches of beer and 90% of them have been made with liquid Wyeast and 100% of them have been purchased via UPS and FedEx. Never got a bad packet of yeast and 100% of the batches turned out A.O.K.
This is another case of someone's "opinion" making homebrewing more complicated than it needs to be.
Back during the days of Henry VIII, there was a particular style of beer that was brewed in England. The strain of yeast used to make that beer had become lost to antiquity and hence that style of beer was also lost. During the 1980's, a sunken british warship was discovered in the English Channel. On board this sunken ship was found several corked and unbroken beer bottles of this very same beer that had been lost. They took the bottles back to a lab and lo and behold...the yeast was still alive. 500 years on the bottom of the English channel in freezing cold and that yeast had survived in those bottles! They took cultures of that yeast, incubated it and now that type of beer is once again made in London. This was a story that I heard on Paul Harvey about 15 years ago and so I don't know all of the specifics. Sorry. Maybe you can Google it. My point is that yeast is one tough hombre!! It can handle a hell of a lot more than UPS, USPS or FedEx can throw at it.
BTW; As I'm writing this, UPS has just dropped my latest order at the front door! Gee......hope my yeast is o.k. LOL!!!!!!!!!!!!! Just kidding. It's just really ironic.