Laptops are outselling desktops and the explanation offered is that portable machines have finally caught up on performance. The first half is true. The second half is not, and I think it also misses why the first half happened.

Take the parity claim first. On a benchmark that runs for thirty seconds, a current mobile processor does look close to its desktop equivalent. Run the same test for twenty minutes and watch the gap open, because the laptop has a heatsink the size of a matchbox and a fan that is already at full speed, so the chip reduces its own clock to avoid cooking itself. Sustained performance is nowhere near burst performance, and every benchmark you see quoted measures the burst.

Everything around the processor is further behind. The graphics chip is typically a generation old and thermally limited on top of that. The disk spins slower than a desktop drive, which is the component you actually wait for. The memory is often a single channel. The screen is worse than a monitor of the same price, sometimes considerably.

So no, parity has not arrived, and it is not going to, because the constraint is thermal and thermal constraints do not yield to process improvements.

None of which is stopping anyone, and that is the interesting part.

The desktop did not lose a performance argument. It lost a furniture argument. A desktop computer requires a permanent surface in a room, and once it is there, using the computer means going to that place and sitting at it. That was a reasonable arrangement when computing was a discrete activity you set aside time for. It stopped being reasonable when computing became something threaded through the rest of the day, done on a sofa, in a kitchen, on a train, half-attentively, while doing something else.

Against that, being forty percent slower is a rounding error. People will accept a great deal of degradation to avoid crossing a room.

What does get given up, and gets counted by nobody, is repair and upgrade. A desktop is a set of parts. When the graphics card is old you replace the graphics card. A laptop is one object, and when the part that fails is soldered, the fix is a new laptop. We have swapped a machine with a ten year lifespan and a maintenance path for one with a four year lifespan and none.

That is a real cost and it is invisible at the point of sale, which is exactly where costs go to be ignored.