It’s not really the same, but it can be enjoyable in its own way. I watch a lot of Let’s Plays, but I tend to do so mostly for games I’ve already played myself, substituting it for a second playthrough. You can watch it mostly in the background - or skip through the filler - and still get another’s perspective on the best bits.

It’s also perfectly valid to watch playthroughs for games you are interested in experiencing but would not enjoy yourself. Very difficult games like Hollow Knight are a common example for this. It will give you an approximation without driving you to frustration - or getting stuck and unable to finish.

It’s never going to be the same though since the interactive element will be missing, and that aspect is the defining feature of games as an artform.