[dullcrisp]

You think no one checks if their arithmetic overflows?

[Spivak]

I'm sure it's not literally no one but I bet the percent of additions that have explicit checks for overflow is for all practical purposes indistinguishable from 0.

[nox101]

Lots of secure code checks for overflow

    fillBufferWithData(buffer, data, offset, size)

You want to know that offset + size don't wrap past 32bits (or 64) and end up with nonsense and a security vulnerability.