You probably don't for personal budgeting and tracking of items for tax purposes. Any run of the mill spreadsheet will work just fine for that purpose.

I'm a chartered accountant though, like think of me as a free agent if you will, I'm not tethered to anything or anyone. I do professional work or give professional advice in exchange for currencies of various origins. My work as such, is a bit more complicated, and I need Excel. Sometimes I have to shared access to files for instance, or I need to share a file with someone, who won't have libre because they are using Excel locked behind a corporate environment they don't control. Libre Calc does have some unique functions that I'd argue Excel doesn't have, but on the flip side Excel has more advanced functions, and xlookup, which I pretty much use every day. Google Sheets isn't even in this conversation, and I personally have a hard dislike for Google Workspace apps in every form.

It would be nice if there was an actual alternative, and I think Libre would probably be the closest viable one. The gap is narrowing. Microsoft Office is atrocious in price, but thankfully easily hackable though, although in a professional environment you have to be more careful with this, than you personally would care to be. It's also a memory pig for absolutely no reason, and so full of historical bugs they haven't cared to fix for 30+ years. Plus some new ones that are infuriating. And you could set Microsoft Word on fire with no complaints from me.