If you're using same amount of paper at the end, why bother with a bigger device with higher maintenance costs?

Edit: Some to same. Big Sur's autocorrect is a bit too aggressive it seems.

So you can save your eyes the strain of trying to read A4 pages at A5 size? Wasn’t that what the original issue was?

Stapling normal sheets from a corner doesn't have a net disadvantage when compared to booklet printing (when reading papers). Booklet allows saving paper by printing in a easily manageable format (you don't need to cut papers in half to read them properly) in a smaller form factor.

So, printing in booklet is just a convenient way to automatically downscale documents, nothing more, at least in this context.