In Mariupol fighting is going on within the city so that's what happens. If you look at previous historical examples, the same result ensues. Stalingrad being a very famous one, Berlin as well, Beirut in Lebanon during the civil war, recently Aleppo in Syria. Before that you can find pictures of the American Civil War. Dresden and Tokyo were flattened during WWII without any actual ground fighting going on there, just large scale air bombings with incendiary bombs...

In conventional warfare since at least the 19th century, cities get flattened.

In the media, and judging by the reactions to this comment, people are driven emotionally in the moment for the purpose of manufacturing public opinion (i.e. war propaganda) but it's always useful to keep distances and keep some perspective. Especially since this is the first large-ish scale conventional warfare in some time, at least with this level of media coverage.