Postels law is the worst kind law ever made in IT. Take a look at how many security bugs that comes from being 'accepting' of bad HTML/CSS/Javacscrip/PDF files.
Be a nazi in what you accept, fail loudly and early enough and there will be no problem for the user to correct his error - it is only when you 50000 php pages full of echo statements that you can't change. If it had complained when he made the first, he wouldn't be in that situation now.
And don't tell me that nobody would use it then. C++, C# and Java are the top most used languages and they are all anal-retentive.
Be a nazi in what you accept, fail loudly and early enough and there will be no problem for the user to correct his error - it is only when you 50000 php pages full of echo statements that you can't change. If it had complained when he made the first, he wouldn't be in that situation now.
And don't tell me that nobody would use it then. C++, C# and Java are the top most used languages and they are all anal-retentive.