Could not agree more. I never use chemicals on normal drains. The only time I remember using a chemical drain cleaner was where the drain was in the slab. X Ray film developer over drain so I could not get a snake in it.
My 1st experience with chemical drain cleaners was sometime in 1968 as a Third Class Midshipman at the maritime academy. Someone had tried chemical drain cleaner is a drinking fountain drain. And when that did not work the pipes had to be taken apart. The midshipman taking the lines apart got some of the cleaner in his face. He dropped the lines and what was in the lines were dumped all over the engine room. He went to sick bay and I got the pleasure of cleaning the stuff up. Remember if you pour dangerous stuff down a drain you may get stuck having to clean it up or calling and paying someone to clean it up.