I firmly believe they've single-handedly set personal computing back 30 years with how terrible Windows and Office are. Windows has been the vector of choice of practically every major worm, virus, malware, ransomware and botnet developer for decades.
Windows Server was so bad for awhile you had to airgap systems while installing it until you'd also installed critical patches separately, because if you left a system exposed to the internet during the initial install it'd be infected before it was even fucking finished installing. Meanwhile the only reason Windows has ever had even remotely decent network performance (which it didn't always have) was because around the time of Windows 2000 they finally wised up to the fact that they couldn't write a network stack to save their lives and just swiped FreeBSD's to stuff into the NT kernel to catch up.
Until Google Mail (of all things) came along, they practically had a monopoly on corporate email, subjecting millions of people to the substandard experience of Outlook. Not to mention how fucking awful the rest of the Office suite is.
Then they started shitting on Linux instead of (legitimately) embracing open source and fostering it, leading to a decades-old OS war that gave Apple the chance to swoop in with its shitty mutant BSD variant wrapped in shiny plastic and terrible UI and establish itself as the "chic" and "hip" way to use computers. Instead of, y'know, two platforms (Windows and Linux) contributing to each other to build stronger end products.
I'll never forgive the Redmond faggots for the years I spent justifying installing Linux on servers instead of fucking Windows Server (or even Solaris on Sun's server line). No matter how many times I turned a $200 pizza box into a blazing-fast firewall and DNS/DHCP server that blew away a $10k piece of hardware running Checkpoint Firewall or showed how Bugzilla could beat the pants off a $100k Peoplesoft "web portal," people always parroted that garbage "Linux is only free if you don't value your time" and "it's free, so it can't be good" bullshit.
They killed Netscape and punished the world with IE6, which the industry didn't fully purge until just a few years ago, decades after the piece of shit was born. They fucked over Digital Research by rigging Windows 3.x to refuse to start on DR-DOS, killed the company that created Doublespace by replicating it (poorly) with the data-eating Drivespace, and nearly killed Mozilla/Firefox until the limp-dicked DOJ woke up for five minutes to spank Microsoft for their bundled browser shenanigans.
