I have always been interested by how seasoned computer professionals are able to do anything using nothing but consumer websites. For example, there are no decent UML, database, network diagram tools.
There is a version of ssh that runs in browsers. Works perfectly well, even with multiple monitors and many ssh windows.
Diagramming tools are all over. For example, I have been using Microsoft Visio (for the last 15 or 20 years), and recently switched to run Visio on the web, instead of installing a copy on Windows. It saves me having to install a Windows "machine" just for running visio.
No serial port access; no disk label utils, etc.
Serial ports are de-facto obsolete. You need them for embedded development, nothing else.
Disk label? As I said above, people today use a desktop machine that has no OS (for example a Chromebook or iOS/Android tablet). There is no disk labels, there are no user-visible disks, there are no utilities. You open a browser or installed canned apps, nothing else.
There is also barely a terminal emulator or grep tool.
Terminal emulator: See above, web-based ssh exists. Grep: That is built into your work flow tools.
How do they even find documents?
Most companies use a Microsoft samba share to store internal shared documents; how are web browser thin clients able to get the data stored there, uploaded to a web server and then viewed using the web services viewer.
You run what amounts to a search engine. You can run it in a server. For example, at home I have a large ZFS-based file system, on a FreeBSD machine, where I store scanned documents (there are tens of thousands of those, I have a paperless archiving system at home). On that server there is a simple CGI page that allows me to search for files by string in file names (20 lines of Python); that already allows me to find files by file name. To find files by a string in them, I have run glimpse a.k.a. agrep before, and made it accessible via another simple CGI script. Alas, that didn't work well: My paper scanning software has really bad OCR built in, so the PDF files it creates have very little searchable content. I need to take all my documents and re-run the OCR on them (and add the text output to the PDF files as another layer or comments). While I know how to do it, it is quite time-consuming, and I haven'gotten around to it.
Have you tried using Cloud accounts like Azure or Google? All your documents are online (and when I say "documents", I don't mean just word files, but databases, programs, queries, make file, spreadsheets, e-mails), and are all searchable.
Perhaps I just don't quite understand what a computer professional is these days.
In my example, typically someone with a PhD (or at least MS) in Computer Science, who works as a software engineer or project manager at a computer company? And doesn't have a "computer" (in the sense of a device with an OS), but uses a lightweight stateless desktop or client (like a Chromebook or tablet) for all their work? This example is quite common today.