Microsoft announced last month that Dell and HP would soon be selling its Surface line of tablets. Redmond asked another big PC seller if it wanted in on this action, but that response was less positive.

Reported by The Register, Microsoft approached Lenovo more than a year ago to see if the world's biggest PC seller wanted to sell Surface hardware. Lenovo president and COO Gianfranco Lanci said, "No I don’t see any reason why I should sell a product from within brackets, competition."

Microsoft's relationship with OEMs is undoubtedly more complex today than it was before the Surface line launched. What was once a software company that partnered with hardware firms is now also a hardware company that competes with them. Acer in particular was critical of Microsoft's decision to launch the Surface, and the launch of the laptop-like Surface Book hasn't helped matters. Asked about the Surface Book last week, Asus Chairman Jonney Shih said that the company was going to have to have a "serious talk" about Microsoft's further encroachment into the hardware business.

Why did HP and Dell decide to sell the competing product anyway? Customer demand. Marius Hass, chief commercial officer at Dell, said simply that enterprise customers with existing arrangements with Dell wanted systems to be "managed and deployed" by Dell. "We could tell those customers 'Sorry, we are not interested because it's a competing product,' or we could say 'Mr. and Mrs. customer, we'll take care of you,' and that's what we did."

This suggests that the Surface Pro has a significant amount of enterprise interest, and the story from HP is very similar. Dion Weisler, who will become CEO of HP Inc., the PC and print division of HP that will soon be a standalone company, said, "These are customers we have been working with for many, many years, and we don't simply want to cede those relationships to a competitor, so we said 'OK, we'll participate in that'." This support is somewhat begrudging; HP salespeople won't receive a commission for selling the Surface, and Weisler said that it will be sold and supported only if "the customer absolutely insists upon it." Not tremendously surprising given that the former partners are now competitors, but nonetheless significant: clearly some enterprise customers are absolutely insisting on the Surface.

Given this demand, it's perhaps not altogether surprising that many PC OEMs are working to build Surface-like systems of their own. Lenovo announced the MIIX 700 in September, Dell announced its Surface-like XPS 12 earlier this week, and HP too is getting in on the action with the Spectre X2. Further afield, both the Google Pixel C and, of course, the iPad Pro borrow more than a little from the Surface's concept. The decision to make the Surface may have made Microsoft a competitor with its traditional partners, but it has also had a clear influence on the shape of the computer and tablet market that reaches far beyond its raw sales impact.