As the article points out, letting people walk up should probably be faster. What causes the block is people misbehaving. Blocking the left line because they want to go on the right line. Stopping for directions at the end of the escalator. Blocking the left line with bags or packages. But the solution should be better education, not slowing everyone down.
It's like letting people out of a car before getting in. In most tube stations, londoners are very courteous and the process is very fluid, even at peak hour. In touristic hot spots in the summer, you pretty much always have a crowd pushing in like a scared cattle. Some poster to remind passengers how things work in the UK would probably do the trick.