People use this to justify just about everything, like being addicted to World of Warcraft for 5 years and forgoing their ambitions to watch Netflix. It's a joke at this point.
It needs to come with a second part "but do your best to set yourself up for life fulfillment" or be refactored into "don't beat yourself up for wasting a little bit of time". Wasting time and instant gratification will absolutely keep you from achieving what you want in life.
Time you “waste” looking out the window, thinking about life is not instant gratification and doesn’t beg you to come back whenever you can. It’s really not comparable to a video game, movie streaming, or social media.
When you consider something wasteful it trumps what another person thinks about the same? Are you using some objective criteria for this? I’m sure something you consider a good use of time is considered wasteful by a good number of people.
So my point is: should I consider binge watching Netflix (random example) as wasted time because you consider it a waste or should I keep doing it because I enjoy it? Especially if objectively speaking it doesn’t prevent me from being a useful member of society, perhaps more so than many people who don’t engage in such “wasteful” behavior.
You can probably find a counter example for most rules you can think of. A cherry picked example doesn’t negate the premises.
Years ago some guy was rambling about shadows in a cave. Not quite WoW but still pretty wasteful depending on who you asked.
Time you enjoy wasting is not wasted time.
At the very least you get to disconnect your brain. At best you come up with something awesome.