There is a big difference between shipping software and deploying software on your own servers.
Of course it is software, but it is not shipped to anybody in a sense that I understand the term 'to ship product'.
Whether by download for installation on end-users computers, cd, dvd or papertape is not the issue, the issue is whether or not the software remains installed on the users machine when they are not using it.
Key difference between a web application (even one with a bunch of client side scripting such as scribd) and a product that actually ships is that you can't modify it as easily (even with auto-update) as you can with server side deployments. If you mess up with a web app, no big deal, fixes are minutes away, hours at worst. When you've shipped product to a few hundred million installations all over the globe and you find a problem, you have a problem.
If you're lucky it isn't going to end up as a 0 day exploit, and it won't nuke your customers machines.
So Q&A in that situation is a lot more involved than it is for most webapps, and the penalties are significantly larger.
For the OP to compare scribd with microsoft in this way and to claim that 'microsoft has no clue how to ship software' is downright silly.