Lots of companies do, mostly because some people find it indispensable, then move to other companies and convince them to use it as well. In my unit, the design team uses Dropbox and the marketing team uses Sharepoint/OneDrive.

Me personally? I used DB back when they intentionally slowed the transfer rate on free accounts to a snail's pace. I'm not sure how this was supposed to upsell me to a paid account, considering I already had Google Drive which was much faster and free.

Never used Dropbox again.

I do. They still store some files for free. I sync daily using rclone. Not broken.