Do you need ND filters to achieve long daylight exposures?

Our photography club tries to have a monthly lesson followed by a workshop. This month the subject was long exposures; our workshop was at the community entrance where there’s a nice waterfall. I have a relatively full ND set so that was simple, but I decided to take it up a notch by trying to simulate ND filter use in camera. I tried 3 different methods 1) HDR taking 7 exposures 2) using the camera’s burst mode, 3) using the camera’s time lapse. I was pleasantly surprised by the results:

    1) HDR produced reasonable results with the least amount of work

    2) Burst mode provided ok results with more work as I noise stacked the set in PSE elements+

    3) Time lapse provided results almost equal to ND filter -same work as #2



#1

#2 

#3 

So it's possible but the results using ND filters is superior, less work in post.