[LnxPrgr3]

Not to mention the effect of time. The Web is not a stable application environment, and you may get caught in limbo, where the old way to do something is technically deprecated, but only one browser implements the new scheme, and only in nightly builds and even then only if you launch with --please-segfault-hourly. But using the deprecated API means at some arbitrary point in the future your working code will stop working.

[asadotzler]

The Web rarely deprecates features. Browsers still have to display the Web of 1995.

[LnxPrgr3]

How about the Web of 2012?

WebSockets changed wire formats multiple times before we settled on something. Last I checked, the API still isn't final, and changes in browser behavior forced a project I was on to abandon it for socket.io. Web Audio has been through at least one breaking rewrite since 2012, and still isn't finalized.

Sure, '<h1>' still gets me a big, bold heading (probably, subject to CSS), but playing a sound file without plugins is still bleeding edge, and subject to arbitrary breakage. But we've broken plugins (for the best, eventually), so the old solution to that problem no longer reliably works.

[dragonwriter]

> The Web rarely deprecates features.

No, it rarely removes deprecated features.