Would or Used to

[McKinney]

Hi, could you please tell me why these two sentences are not correct?

I remember we would go fishing every morning when I was a child. It was great. Now, I am an accountant and I don't have any free time.

My grandfather would swim in this river. Unfortunately, now it's forbidden.

I can't find the reason for "would" to be wrong.

Thank you!

[Alan]

There is nothing grammatically wrong with either!
Referring to an habitual past action is a perfectly legitimate - if slightly literary - use of 'would'.