Why don't we all use code editors that know how to render things like Graphviz and Markdown with lists, tables? Maybe in a side window rather than in the main

Why don't we all use code editors that know how to render things like Graphviz and Markdown with lists, tables? Maybe in a side window rather than in the main display, but like, come-on... Like, Visual Studio Code supports something like this: https://marketplace.visualstudio.com/items?itemName=joaompinto.vscode-graphviz https://marketplace.visualstudio.com/items?itemName=joaompin...