Recently I have seen more and more people here who claim they are native English speakers, but their grammar looks horrible.
Using 'am' instead of 'I am', writing 'I' as 'i', missing articles and a lot of typos.
Some of them pretend to be from the US or UK, others from countries where English one of the official languages.
Who are they? Scammers, just not educated people or youth with a new trend in internet communications?
There has always been a small number of italki members who pretend to be native language speakers.
The types of mistakes you've identified would not be made by native speakers who respect the language.
So, are these people pretending to be native speakers or are our language skills deteriorating?
from Princeton University...
Recent graduates, including those with university degrees, seem to have no mastery of the language at all. They cannot construct a simple declarative sentence, either orally or in writing. They cannot spell common, everyday words. Punctuation is apparently no longer taught. Grammar is a complete mystery to almost all recent graduates. Attitudes toward English Teaching, 1961
From every college in the country goes up the cry, "Our freshmen can't spell, can't punctuate." Every high school is in disrepair because its pupils are so ignorant of the merest rudiments. 1917
The vocabularies of the majority of high-school pupils are amazingly small. I always try to use simple English, and yet I have talked to classes when quite a minority of the pupils did not comprehend more than half of what I said. Methods of Study in English," 1889
Unless the present progress of change [is] arrested...there can be no doubt that, in another century, the dialect of the Americans will become utterly unintelligible to an Englishman... 1833
Conclusion: There will always be those who do not respect their language