Bikkurim, Chapter Three, Mishnah Seven
Evidently, not everyone knew how to recite the bikkurim verses from the Torah. Originally, to remedy this problem someone who knew how to read would read the passage and the person bringing the bikkurim who did not know how to read would repeat the words after him.
The problem with this is that it was embarrassing for people to admit that they couldnt read. To avoid this embarrassing situation, people stopped bringing bikkurim altogether. It is interesting to note that already in ancient times people feared having to make public liturgical declarations. This is reminiscent of people who might not come to synagogue today because they fear being embarrassed at not knowing how to say the words or not knowing when to sit or stand.
In order to solve this problem, they instituted that the recitation would be read to everyone, so that everyone would have to repeat after someone else. This way no one would be singled out for embarrassment. Note that the rabbis didn’t just say, Let them learn how to read. That might be desirable, but would probably not solve the problem of people not bringing bikkurim. Rather, they found a solution that would prevent people from being embarrassed, allow them to bring their bikkurim, without forcing them to have to spend years of their life educating themselves.
1) Originally all who knew how to recite would recite while those who did not know how to recite, others would read it for them [and they would repeat the words].
2) But when they refrained from bringing, they decreed that they should read the words to both those who could and those who could not [recite so that they could repeat after them].