[dirkt]

Wrong question: It's not a competition.

There are cases when you have some complicated json and just want to search for stuff. Then you use grep + gron.

There are cases when you want a complete json processing tool. Then you use jq.

You can probably simulate each approach with the other approach, but the code needed to this is just too tedious to write. So you use whatever tool fits your use case.

[nerdponx]

No, but you still have to make a decision about which tool to use. So it's helpful to have a sense of the use cases for each.