It's common for many, especially members of the mainstream medical profession, to be ignorant of the importance of probiotics. While antibiotics that turn gastrointestinal tracts into killing fields are routinely prescribed, probiotics to replace lost beneficial bacteria are rarely even suggested.
Even when a doctor does give that advice, it's from the mindset that probiotics are merely important for good digestion. True enough, but probiotics, or good gut bacteria, need to comprise at least 80% of total gut bacteria for several other reasons.
Several tests and clinical studies have confirmed a strong probiotic presence with an 80/20 or 85/15 intestinal flora balance is necessary for several reasons.