The companies I worked with primarily developed on the systems customers used. You really want to see the issues on your tier1 platform as you develop. Linux

The companies I worked with primarily developed on the systems customers used. You really want to see the issues on your tier1 platform as you develop. Linux was not tier1 at that time. This meant that code written on Sun that performed well performed poorly on HP-UX occasionally -- not because HP-UX was a worse platform, but because corner cases in architecture could bite you. On your tier1 development platform you tend to weed those issues out early.