Eh, intellectual property is favoritism. By claiming Microsoft is entitled to only being able to shape bits and bytes a certain way is denying everybody else to do the same with their property. It is an infringement on property rights inevitably.
Right, but that protection isn't unique to microsoft. It also applies to apple and other companies. This isn't an offensive argument in any way, precisely because everybody could've had this.
Furthermore, this isn't targeted favoritism. Why are ideas any different from physical property, or patents? I'd say they weren't unfairly favoring anybody, but rather protecting property rights.
Finally, the alternative(unrelated to the debate if IP= subsidy) is much worse-- artists could have their masterpieces photocopied and sold if there were no copyright, IP rights.
But yeah, I don't think that Ip could be a subsidy in any meaningful way. And if it is true that this specific type of subsidy made microsoft into a corporation, then you'd have no problem citing other examples wherein copyright laws/IP gave a monopoly on an industry that was meaningful in some way(IE, direct casual relationship).