the weird "the extent to which"

[peteryoung]

The researcher remained impressed with the extent to which MANY journalists were convinced that editorials had an effect on other people's attitudes, while discounting the effect on people like themselves.

I don't know why there should be a 'MANY' in this sentence. I think the phrase 'the extent to which' is like a scale and the result of measuring could be either small or large . If we eliminate the word MANY and say "the extent to which journalists were convinced ..", it's like we have defined a variable which represents how much the journalists were impressed. But when MANY is inserted, it's not clear to me what the researcher was impressed with. Is it the 'extent', which could be either large or small and is ,in this case, large by context, or is it the fact that MANY journalists were convinced?

Wouldn't it be clearer to eliminate MANY?

Any reply would be appreciated.

[Spiral]

To me, many is a bit redundant, but I think it's there to show that the researcher was impressed with the high number of "journalists [that] were convinced..."

[peteryoung]

Thanks again,spiral :)