People on the internet can be anything they want to be. In actuality, your lack of knowledge indicates you know nothing about mainframes. SPARC is not a mainframe, by the way, it's a workstation class chip, that doesn't compare to IBM mainframes. You wouldn't know, because you know nothing about it.
Anyone that thinks Windows can replace MVS derivatives is plain ignorant of the differences of the two. Or that these toys you play with offer anything close to the security and reliability of a mainframe. You simply don't know. Learn.