First paragraph claims that hostile architecture discourages “anti-social” behavior.
Skateboarding and sleeping in the park is not “anti-social.” Instead, these activities don’t make anyone any money, and might even lose money. That’s anti-commerce, not anti-social.
Public spaces that support the needs of the _entire_ public foster stronger communities than those that only support commerce for the professional class.
Skateboarding in areas not designed for it is anti-social because other people can't use (or even just safely walk through) the space for risk of having someone crash into them. Even though I believe skaters are not being deliberately obstructive of other users, and most likely will happily wait for people to go past and for the space to be clear before attempting whatever trick they're trying, the fact is that a lot of people find it off-putting.
This should not be surprising and is not an unreasonable reaction. Consider that skating (often) involves moving fast through the space, in ways that are not easily predicted by someone who isn't themselves a skater. Practicing tricks necessarily involves making a lot of mistakes so people and boards can go flying in unexpected directions. Skating is often done by groups so there can be several people doing unpredictable things at once. And people (both skaters and others just trying to walk through the area) often have poor situational awareness. The whole thing is a recipe for accidents. And that's totally fine if it's happening in a skate park, but it's anti-social when it's happening in a normal public area that needs to support foot traffic.
None of that is related to commerce or specific to the professional class.
Are these also used as deterrents to terrorism via motor vehicle? Large blocks of concrete to prevent cars and trucks from intentionally going onto the sidewalk to harm people (as we've seen a couple of time in Europe.)
Edit: after looking at the pictures closely it does not look like they have been placed in such a manner that they would be so I guess the answer is no.
Why can't we polish concrete more? Buildings and benches would be so much more attractive. Perhaps more weather-resistant too? But pavements slipperier when wet...