The current president isn't the only one to blame, though. For the past 15 or so years, the government relied more and more on China to basically keep its wheels moving at the comfort of endless projects funded by China. Sri Lanka used to manufacture a lot of things such as tyre, sugar, paper, etc. The over reliance on imported goods didn't play out well, and things such as tyre, sugar, and paper are now at a shortage because the government simply didn't bother to improve the local manufacturing of said goods.
There may well be something to institutional economics and the notion of a holon.
There are some loosely imposed rules that one cannot buy more than 5kg of rice per turn, etc. But I don't see people actively hording things. The long lines are likely because a shop is only allowed to bring in 2-3 customers at once.
This is why moderate inflation around 2% is good because it stops hoarding of money and why inflation above 10% is destructive because people start hoarding goods.