I can't remember the last time I received a file from someone that I couldn't use.

These days, the file formats we use are pretty standardised. PDF files, Word documents, JPGs, MP3s, MP4s and so on - unless the person sending you it is a specialist in some area you actually have very good odds that any file you're sent will be readable.

Of course, it wasn't always so. But it was once much worse than just having different file formats. WordPerfect vs Wordstar vs Word was just an argument between companies. Once, it was a battle between computer hardware and countries.