is simple to introduce such a option than to apply alternative ways to do it..
I guess I just don't believe this is true. It seems much simpler to say "pin mIRC to the taskbar like you can with every other program" than to try to help a user find this setting in the plethora of mIRC's existing window management options.
It's one thing to add yet another setting to mIRC-- seemingly easy to implement, maybe. But adding yet another setting to mIRC does not automatically mean users will know it exists or where to find it. The difference now is that one of these explanations involves a one-off solution that only works with mIRC, and the other works OS-wide, and is invariably the recommended path forward from Microsoft's perspective. If you have to choose between giving a one-off explanation or one that works for any program, my guess is you would choose the latter.
More importantly, as users start to learn about the taskbar pin functionality in Windows 8/10+, they will eventually stop having this problem in the first place, as they will already know how to manage this issue for all programs. Basically, the multiple instance problem is becoming a legacy issue as Windows introduces new UX paradigms. mIRC gets dinged quite often for being behind on the times when it comes to UX (still using MDI, heavy use of menubars), it seems odd to me to add new features that specifically target problems that are inherently legacy issues. Instead, mIRC should be promoting Windows' new paradigms-- and frankly, that means disabling the default "minimize to tray" behavior-- which would go a long way to solving the multiple instances issue.
