It’s when you’ve created 10 reports, all doing different levels of ETL from 10 different BAQs and you have calculated fields in each of the BAQs named different things that have the same formula and someone asks you to update the formula for X, so you now need to go back track to which BAQ has that custom field, what the change is going to do, etc.
I couldn’t agree more to hold off on stuff till you need it, but in BI, I didn’t realize I needed it till it was too late. And the idea of having to re-do all of our pipelines, queries, etc. when I could have just done it at the start… that’s the hard part.
Just my two cents with BI. I’m not an expert, still learning more, but it only gets more complex the more your data needs grow. That’s also why I posted the thing from AI saying “For small/simple scenarios, direct Power BI queries can still be fine.”