I agree with you. The reason such errors worry me, even if clarity isn't an issue, is that the next generation reads these incorrect texts and assumes that everything they read was written correctly. As a consequence these kids misunderstand the grammar of their language. Lack of formal grammar training doesn't help. Because language is an important tool for thinking, degraded language skills lead to degraded thinking.

The example that always gets me foaming at the mouth is the persistent confusion of "are" and "our" in online forums, just because they sound similar in an American accent.