This was true 10-15 years ago. It is no longer true. Chess engines have positional evaluation algorithms that have been trained using many millions of games, and the weighting parameters for different kinds of positional features have been adjusted accordingly.

Do some reading on Stockfish for example if you doubt the veracity of my statement.

Yes, I do realize that.

But its just as you say: its weighting parameters and heuristics. When Stockfish recognizes a backwards pawn, it deducts a point value. When Stockfish recognizes "pawn on 6th row", it adds a point value to that pawn.

But that's a heuristic. A trained heuristic using games, but still comes down to what I understand to be a +/- point value (like... +35 centipawns).

In contrast, a chess engine truly knows that if you do X move, it will force a Rook / Minor piece exchange in 8 moves.

When you play positionally vs Stockfish, you're arguing with a heuristic (a heuristic which has been refined over many cycles of machine learning, but a heuristic nonetheless that comes down to "+/- centipawns") . When you play tactically vs Stockfish, it is evaluating positions more than a dozen moves ahead of what is humanly possible.

When you play against Stockfish in endgame tablebase mode, it plays utterly, and provably, perfectly.

Take a pick of what game you want to play against it. IMO, I'd bet on its positional "weakness" (yes, it is still very strong at positional play, but it is the most "heuristical" part of the engine)

If this is true, why do computers regularly and consistently defeat even the best humans in full games of chess that last dozens of moves?

Because they beat humans at tactical play, like he said. Just because something has a weakness, doesn't mean it isn't better.