This is not true.
Only SMIPS devices (I think only hAP Lite is using SMIPS) force you to use Winbox 3.
All other architectures still allow you to connect using Winbox 2 (thank god!)
It somewhat works, but multiple problems with WinBox 2 + recent RouterOS versions have been reported here on the forum. I clearly remember someone complained that a whole bunch of wireless options is missing, and something does not work as expected. The official statement from Mikrotik in such cases is “use the latest WinBox”.
I use winbox, all day, everyday, and I have no problems whatsoever with v2 on all architectures for which I have routerboards or x86 installations.
All my installations are up to date (6.38.5).
From time to time there may be a bad release which might break something either on winbox or any other access method (webfig,cli,api).
But that’s not a v2 issue.
I can’t say the same for winbox 3 though. It’s just not production ready. Missing features, crashes, bad UX, generally a beta software at best…
MikroTik’s de’facto position is always “use the latest version” no matter what issue you report to them 
Thank you for that detail - which is NOT intuitive! So you just have to know it, I guess.
Can someone explain why I sometimes get WinBox version 6.28 and WinBox Loader version 2.2.18?
As far as I know, I only downloaded one Winbox executable to my WinXP desktop and that is shown in the screenshots as WinBox v6.28 above.
Yet, in one of my screenshots, running that Winbox pops up a box that says “WinBox Loader v2.2.18”.
Where did that “WinBox Loader” come from?
I didn’t install it (that I know of).
MikroTik RouterOS 6.28 is the version of MikroTik itself.
Winbox 2.2.18 is the version of the winbox tool.
So, you are using winbox 2.2.18 to connect to mikrotik 6.28 