Little has changed, except it's coffee and Spotify for me. Keep in mind that back then, wine / beer were an important source of clean drinking water, and it would often be low alcohol.
Maimonedes Human Dispositions 4 (Trans. by Eliyahu Touger)
The great Medieval water myth (2013) - https://news.ycombinator.com/item?id=9031856 - Feb 2015 (71 comments)
More times than not it will not be stronger, it will be compounds that are not psychoactive at all, effectively “cutting” the potency of the substance while multiplying the quantity.
There are cases with fentanyl where a stronger substance is mixed in with the original and this often is what you read about in the news, but it is not in generally in the distributors best interest to be killing their clientele.