Can you operate QB desktop from a company file in dropbox which would make it essentially cloud based?

I would only recommend storing QBD data file on a cloud storage (e.g GDrive, DBox) for the backup purpose. You should download the data file locally anytime you want to work on it, and reupload back to the cloud later. Some of our clients have said that their data files tend to corrupt when opening it direcly to the cloud. 

https://quickbooks.intuit.com/learn-support/en-us/account-management/want-to-use-qb-on-two-computers... 

Yes, I've seen that, but it's just a 3rd party opinion, it's not from QB or even a QB user.

I have come to agree with Fiat Lux. I recently moved to TopBox for cloud storage which automatically syncs from my local hard-drive to the TopBox cloud. I have run, literally, dozens of tests. Quickbooks Desktop cannot open the Company File, not matter how I try to do it. It always fails. I must first copy the file from the cloud to a local drive that is not being linked to the cloud. Do my Quickbooks work. And then, copy the file back to the cloud. In my case, I only copy the QBW file. That file is all that is needed for Quickbooks to open the Company and generate all of the other needed Quickbooks files.

We don’t like using Dropbox because it comes with risks and limitations that make it unreliable. Dropbox isn’t built for this, so syncing can corrupt data if two devices attempt to access or update the file simultaneously. Additionally, performance issues often arise due to delays in Dropbox’s syncing process, especially with large files.

You can try solutions like Splashtop or TeamViewer allows you to access your office PC running QB Desktop directly, maintaining the integrity of the file.

Alternatively, you can also use cloud-based 3rd party tools like Skyvia. This tool is efficient and requires no code.

But as I said, to achieve a true cloud-like experience without risking your data, consider these options instead of using Dropbox.