Do have a 7 MiB file, you would need a HD at least that size. In reality even a manyfold thereof, as usually one won't have a HD with just one file.
Now, in the real early times, lets say 70s, home users wouldn't have disks at all - not even floppies, and professional users with minis would use disk packs (exchangeable hard disks) and maybe fixed disks of the same or similar size. So file exchange wasn't a big deal as the disk pack could be just mounted on another machine. In fact, it would be more of a challenge to find another user to exchange files in the first place:)
Now, 40 years ago, that would be the end of the 70s (1978). If at all, SOHO users would have a disk drive. And while HDs where already available, one would rather invest in a second or third FD than putting up the same amount of cash as a small car to get a HD. In that time-frame a professional disk drive was good for anywhere between 200 and 600 KiB So a 5 MiB HD was barely more than a dozen floppies. Again, not worth it.
The situation stayed the same throughout the majority of the 80s. Hard disks where only available at high end machines out of reach for most users. Also Floppies reached 600 to 800 KiB. Quite a lot. Keep in mind that back then most applications didn't store a lot of meta data, and if at all, they did it in rather efficient way. So instead of adding like up to 300 bytes to a text file for making one word underlined in MS-Word, WordStar just added two bytes (well, 7 in some cases). Thus text files didn't require much more space than the amount of letters typed.
An average business letter back then was often less than 2 KiB on disk. So having a hundred letters on one FD wasn't anything unusual. Even a large thesis could fit on a single disk. Serious, I have a hard time to imagine larger databases on micros back them
Just an example, on mainframe system I worked on in the first half of the 1980 got all databases stored on two 144 MiB drives (plus another for the OS). That was the only IT system for a company with about 1500 employees and storing next to everything on these two disks.
In the micro range the need for archives spread out over multiple floppies didn't emerge before the late 80s/early 90s, when average HD size grew beyond 40 MiB and more important data processed moved away from simple text and numbers to more complex objects that could produce files in the MiB range.
And users growing into this range didn't use floppies for data exchange. The mid 80s to late 90s were the heydays of changeable hard disks (Syquest et al) and more important QIC streamer. I still remember, when I ordered a first 486 (with a 170 MiB ESDI) or later a dual Pentium II, I took care to include a QIC streamer for backup and data exchange. Many may also remember the surge for ZIP drives during the late 90s, for exactly the same reason: Data exchange and backup.
This is also the idea where SuperDisk / LS 120 originated. A way to exchange larger fines in a floppy like format. They did get some foothold, but where ultimately killed by a throw away solution, the writable CD. Cheap drive and dirt cheap media.