Why is there so much confusion about hotplates on shabbat? With or without a blech, putting cold solids or semi solids straight on without or with an upturned lid?
Like many rabbinic prohibitions, for which there are various leniencies, authorities discuss how far the leniencies go. In this case, one of the basic questions is how far the leniency of “not derech bishul (way of cooking)” goes. Do you need an pot that is full of food, or is an overturned pot sufficient, or is there no problem with a hotplate because people don’t cook on it? It is a delicate issue, and this is why there are different opinions among poskim. Please see some previous posts concerning hotplate-related questions, in which we have expounded on the halachic angles of the issue.