Whenever the reasoning starts with “modern IDE” does this or that, the argument is wrong. Dead wrong.
Not all modern IDE are alike in what tools they offer and how reliable they are. JetBrains IDEs implement most tooling in a proprietary way but they also cost a lot. What you’re saying then is “you can forget some coding conventions as long as you can fork the money for IDEs like that” because for others (think vscode, vim, sublime) they implement plugins and language servers that may be influenced by lots of bugs (even external factors).
Also, some conventions like scope declarations and bracket alignments are useful for coders that didn’t grow up with colorizers – I also look at alignment first (hell, yesterday an error in a terraform file broke my terraform plugin in both vscode and webstorm – had to rely on my eyes to find the problem and then the plugin started working again)
Finally, some conventions also help interpretors and compilers performance.