PowerPoint is a powerful way to quickly deliver development ideas via wireframes. PowerPoint already has the superb delivery to show your designs, something other wireframe tools struggle to do cleanly. Through the PowerStory add on you can quickly develop a storyboard that is easy to print and share with development teams.
At the BAPDD 2013 conference I presented an overview of wireframing and some of the available tools. The presentation included discussion on the use of:
When I polled the attendees, 100% of them indicated they have Microsoft Office available for use. That makes wireframing via PowerPoint a quick and easy option for many people. At the following link is a copy of my presentation which includes a PowerPoint wireframe example built before your very eyes and a tool reference list, Wireframing_An_Overview.
I highly recommend the use of PowerPoint for wireframing. PowerPoint is a way to quickly put together finished (high fidelity) or rough sketch (low fidelity) wireframes.