Office 365 is absolutely not what you seem to describe. I run a small non-profit and I am banking hard on Office 365 while I use a Mac.
O365 is the Office suite of apps, an Exchange server, OneDrive with a ton of storage, access to unlimited Teams meetings, and tons of doodads and doohickeys we don't need. That my Windows using colleagues could potentially install Enterprise Windows on their own laptops (we're a BYOD employer), is irrelevant for us. Any fleet of trashy PC we need for frontline staff already comes with a Windows license.
I agree with your overall point but I'm starting to regularly see older M series MacBooks on sale for around 600 or 700 dollars brand new. Maybe they are using the strategy of selling older hardware for less like they did with the iPhone SE.
A $600 - $700 Dell laptop's CPU does not come anywhere close to an M4 Macbook Air, which you can get right now at Best Buy in a 15" version for $999.
The Mac will also have a faster SSD and (not sure about this) a faster memory bus architecture. And a better GPU and better ability to use Thunderbolt docks / have 3 external 4K displays.
CPU is almost never a limiting factor for workers. RAM is since they generally need a keep a bunch of browser tabs open to memory hogging things like Outlook/Teams/JIRA but RAM speed they probably won't notice.
If they have 3 external 4k displays, their company will probably shell out for Macbook.
The thing is, the storage on Apple devices is so unbelievably fast, you can get by on 8GB just fine. Even with clogging up hundreds of Chrome tabs. Swap is barely noticeable.
Memory management on Windows devices in contrast is utterly painful. The RAM itself is already slower simply due to physics (can't beat the SoC proximity with anything socketed), storage I/O usually has to cross through a lot of chips (same thing, Apple attaches storage directly to the SoC), and then the storage itself that you find on cheap devices is actually SATA under the hood or bottom of the barrel NVMe, no competition at all to Apple. Oh and the storage and RAM are both adequately cooled on Apple devices, so Apple can drive them much much harder unlike the Windows world where often enough the only thing that gets cooled is the CPU and GPU.
Yes, I do think Apple wants far too much money for RAM and SSD storage upgrades, but it's undeniable that even the more expensive ends pack a lot of punch.
MacOS is good option BUT cheapest laptop option is 1000 bucks. Dell has 16 inch with 16GB of RAM for 600.
There is Linux but Linux Desktop still is not ready and mass management of it is very painful.
So you default to Windows. It works-ish, won't break the bank and just about every piece of software you need works with it.