Mobile web app, "tab bar", useable or too obtrusive to bottom native browser controls?

I've never seen a case of someone using a tab bar in a mobile web app, but I think the idea has some merit.

I can understand that the actions may be hard to click because they'd be right above the native browser's controls, also since bottom tab bars are rarely used, the user may be instead looking for an upper nav bar and completely miss it.

Does a bottom tab bar seem completely ridiculous, or might there be some use to it?