Hudson Yards is one colossal, inhumane, sky-blocking cluster of ugly buildings for billionaires. Or so say urban “experts” sentimental for last century’s low-rise Manhattan of small shops and serendipitous sidewalk encounters celebrated in Jane Jacobs’ 1961 book, “The Death and Life of Great American Cities.”

So how come Hudson Yards is full of smiling, selfie-snapping strollers who can’t get enough of the place? The No. 7 subway line, which was often near-empty west of Times Square, is so crowded since the complex opened March 15 that it could do with more trains. Everyone’s clamoring to climb The Vessel, restaurants are full and seven floors of stores both expensive and cheap are teeming with shoppers and browsers.

If history teaches us anything about new urban architecture, it’s this: Ignore the critics and follow the crowds. New Yorkers love most every new project that’s sneered at by architecture snobs.

So what’s the beef with Hudson Yards, which has brought life and commerce to what was, for a half-century, an unsightly open pit?

Detractors whine about everything from exaggerated “subsidies” to a shortfall of women chefs at the restaurants. But the most common theme is that — cue the Gershwins! — it isn’t Rockefeller Center.

The Wall Street Journal’s Michael J. Lewis opines, “Hudson Yards, it is now clear to see, is no Rockefeller Center … it lacks the gracious integration of outdoor space with the architectural order of its surrounding buildings.”

New York Times architecture critic Michael Kimmelman writes that while Rock Center chief architect Raymond Hood grasped “the difference between scale and size . . . and how the success of a neighborhood and its retail businesses come down to what’s happening at street level, Hudson Yards barely acknowledges any of these things.”

True, Hudson Yards developer Related Companies invited a bloody nose by repeatedly boasting it’s the biggest private real-estate development in the US since Rockefeller Center — implying it deserved to be regarded in the same aesthetic league. And the original, landmarked Rockefeller Center between Fifth and Sixth avenues and between 48th and 51st streets is unanimously, and justly, praised as a work of genius.

Hood’s vision isn’t portable from Midtown to fringe locations, but the desire to replicate it so obsesses architectural deep-thinkers they can’t think straight. (In 2003, the Times’ Herbert Muschamp wrote, presumably with a straight face, that Brooklyn’s Atlantic Yards would please “those who have been wondering whether it will ever be possible to create another Rockefeller Center . . . Here it is.” Alas, he didn’t live long enough to see what a fiasco the site, since renamed Pacific Park, would become.)

Nothing so large and serving so many purposes as Hudson Yards…can be fairly sized up without the passage of time.

With the peanut gallery of design eggheads baying at the moon for the next Rockefeller Center, Hudson Yards never stood a chance to win their hearts and minds.

Nothing so large and serving so many purposes as Hudson Yards — 100 stores, a climbable 15-story sculpture, millions of square feet of offices, a new park and other public space — can be fairly sized up without the passage of time.

Even Rockefeller Center was by no means universally loved at first.

As related in Daniel Okrent’s splendid 2003 book, “Great Fortune: The Epic of Rockefeller Center,” urban planner Lewis Mumford sneered that its design reflected “the canons of Cloudcuckooland” and that if it was “the best our architects can do with freedom, they deserve to remain in chains.” Another architect wanted it to be completed “as quickly as possible” so that “the sooner we shall be able to clear the ground and begin again.”

And yet, four years after the first buildings opened in 1933, George and Ira Gershwin wrote, “They all laughed at Rockefeller Center/now they’re fighting to get in.”

With people already fighting to scale The Vessel, Hudson Yards has proved itself a hit in just four days.