The problem with separating out tools is that the resulting tools tend not to work very well with each other and suffer as a result. I'll use gdb as an example: using it standalone means I can use whatever text editor I prefer to read the code, but now I'm forced to manually schlep between the debugger and the editor to do debugging: let me figure out what file I need to look at for this current function, and manually open it in the editor. Okay, now let me copy-paste this function name to break on. Oh, here's a value I want to inspect, let me go manually type this in. And constantly back and forth between the editor and the debugger.

Having the tools all work together in one environment is honestly a far superior experience than having each tool live in its own bubble and requiring you to do all the coordination work yourself, with all of the repetition and scope for mistypes in the process.