The problem with flexible drain piping

What is wrong with using flexible piping under a sink?  They sell it at the home improvement stores and it’s only drain piping so its not supply piping that would be contaminated?  The problem is two fold.  The ridges collect debris and bacteria and can lead to clogs.  If the flexible piping is part of the P trap itself, it is harder to get a good seal to prevent sewer gases from coming through the P trap.  For more information or to book an inspection, please visit www.cornerstonehi.com.