I don’t think that “failing to reject the null” is the same as “accepting the null”. In my own words, I see “failing to reject the the null” as being open minded and “accepting the null” (without being 100% sure) as being close minded. If someone tells me that the sky is blue (Ho= the sky is blue), I will definitely fail to reject the null it if someone else is stating that it is green (H1= the sky is green). But I will also ask my self if the sky it self is really blue. The sky appears to be blue because of numerous factors (ocean, our eyes), but sometimes it is black and even orange. It means that I am still “failing to reject the null” but I am not “accepting the null”. In other words, I agree that the sky is not green but I am not 100% sure that it is blue.