I actually don't believe in that principle. If there is a spec that everyone agrees upon, violations should be accurately and loudly diagnosed and rejected.
Both preparation of the data format and processing of that data format should be conservative. Being liberal in what is accepted has unintended negative consequences.
I agree on principle. But when Marie in accounting opens the CSV that Bob from customer X sent her, if software A opens it and software B screams "error!!!", she's going to use the one that "works". And that means B's vendor will make their tool liberal of what they accept too.
Similarly for websites, that's why browsers fixes what they see rather than not showing what you are asking it to show.
Does it lead to a worse state of things for clear format, with more errors in the wild and no actual reference to base yourself on ? Yes. But it is still what end users want.
Comments
I agree on principle. But when Marie in accounting opens the CSV that Bob from customer X sent her, if software A opens it and software B screams "error!!!", she's going to use the one that "works". And that means B's vendor will make their tool liberal of what they accept too.
Similarly for websites, that's why browsers fixes what they see rather than not showing what you are asking it to show.
Does it lead to a worse state of things for clear format, with more errors in the wild and no actual reference to base yourself on ? Yes. But it is still what end users want.