Windows 95 was fundamentally broken as if I recall correctly there was much less security features (accounts, file permissions, etc.). Nowadays there are less problems with it.

Its not that it was broken, its that security was not really a thing. You had your antivirus to protect you from people adding stuff to discs, but thats it. Windows 95 was just an exe file in the windows folder that you could run from DOS.

Windows NT / OS2 did have more security as it was meant for shared environments, but even there, corporations ended up using stuff like Novell NetWare to get the actual networking services.

Windows 2000 was the first version of consumer windows based on the NT kernel instead of the DOS / Windows 95/98/ME based systems. I still remember running around the office updating windows 2000 machines to service pack 4 to protect us against the first real massive virus "ILOVEYOU".

Edit: Still on first coffee, sorry about the ramblings

Sure, my point was that even if iPhone ecosystem is more secure than Windows 95, I do not think this is due mostly to the "walled garden", but because (as you mention) Windows 95 just did not care about security at all. By the time iPhone appeared the security of Windows systems (2000 and later) had already improved (even if not perfect) and there was a possibility to configure it more "locked down", if you wanted.