Government portals, exam boards, embassies and job sites often refuse files above a fixed size, and the limit changes from one form to the next: 100 KB here, 300 KB there, 2 MB elsewhere. Ordinary compressors only offer "low" or "high" compression, so you end up trying again and again.
This tool works the other way around. You give the limit, and the compressor searches for the mildest settings that reach it. Images are compressed first and the text stays sharp. If the target is very small, the pages are turned into compact images as a last step, and you are told if the limit cannot be reached at all.