[fizzbatter]

Unfortunately that still leaves out a ton of users. I know that's a tiny percentage, but tiny nonetheless. The shop i'm heading to soon has a small number of clients (<5k, each being very important), but with many using ancient systems. IE8/9 iirc. We use Table layouts for our "old compatible" product, and i don't think we'll ever move on from that. Some clients just refuse to update it seems.

Luckily (for my sanity) we have a "new age" product that we can use responsive layouts for.

[gotofritz]

Supporting old browsers should be treated as a special case though, like "people with js disabled" or something. Then of course you don't use flexbox (or serve different css fles or have a scaled down design or whatever). But the "norm" is that flexbox is now safe for most users.

[gbog]

"Refuse to update" well yes, I would too, refuse to do something that is notoriously breaking a lot of working stuff for no known benefit. For example java applets developped for IE6 that is vital, because it drives the 10 years old exotic scanner, and nobody dares touching it.