If that's the case, Empire fails miserably as a movie. It begins with characters we're only properly introduced to in the preceding movie, and opens with Luke talking to a ghost with no real explanation and using magic powers we have no idea how he got (and are never really told the origin of, because ANH showed his introduction to it).
It ends on one of the biggest cliffhangers in cinema history, with Luke having just discovered that the big bad guy is his dad, Han is maybe dead and is being given to somebody named Jabba we've never met, Lando is god-knows-where, and the Empire's power and reach are growing unchecked.
It's because of its place as part of a trilogy that we forgive these glaring issues. In fact, these cliffhangers and plot holes are part of what makes it so great--we know what's come before and we know to expect answers in the movie that follows.
But on its own (the metric by which you say TFA is crap), if viewed by someone who had never seen ANH or ROTJ, Empire is an unsatisfying and confusing mess.
Though I agree with some of your points, the situation between TFA and Empire is pretty different, and I have the same problem as him with TFA. The main issue separating them is that TFA relies on
future films to have
it's own plot make sense. Whenever I bring up Rey using the Jedi Mind Trick (one of the worst scenes in the film in my opinion, and the main reason I can see why some consider her a Mary Sue, since, my god, that felt like it came straight from a bad fanfic). It constantly teases you about the characters' pasts, telling you that you'll get answers... as long as you pay roughly 40$ to see both films in theaters. Rey's vision is probably the worst offender in that regard.
Empire, on the other hand, doesn't rely on any future films for its own plot to make sense. It assumes that you've watched the previous entry in the series, but that's all. It doesn't bring up any plot points for RotJ to explain. Sure, Vader may have revealed himself to be Luke's father, and Han may be frozen in carbonite, but the heroes are safe and are ready to go rescue Han. The final shot is them looking out the window at the nebula, ready and determined to get their friend back. And with that shot, you can assume that the heroes will go and make things right in the next one (which they do). Also, when Empire brings up an element of the SW lore, it usually explains it right then and there. When Darth Vader denies killing Luke's father, he doesn't just say no, he says "I am your father" as well. If TFA did that scene, it would probably just have Vader denying it, and then saying "You will never believe what actually happened to your father" when Luke throws himself off the platform, and they wait until the next film before explaining that Vader was Luke's father.
That's the main difference between the two, and why TFA fails. When Empire expands the lore, it fills in as much as possible. Sure, you could wonder about the exact series of events that led to Anakin becoming Vader, but you're not wondering who actually killed Luke's father. TFA, when it expands the lore, leaves a lot of holes. How did the First Order get so powerful? Who is Rey's family? (Remember that in the OT, they never used Luke's family as a carrot stick. Anakin is explained in ANH, and when the fact that he has a sibling is revealed, the audience is told its Leia in the same movie.) It feels cheap how TFA is relying on future films to have its own make sense, while with Empire, it feels like a natural, fair progression that only relies on what the audience already knows if they've seen the previous films in the series.
