If your street full of esoteric expensive artisan stores was replaced by a Wall-Mart, you wouldn't call that gentrification. Gentrification casts out the low-income residents, it doesn't invite them in en masse.

Actually, that's typically what does occur as part of gentrification. Typically a bohemian neighborhood has all sorts of interesting indie stores selling books, art, antiques, etc. But these stores aren't that profitable -- a chain retailer can pay much more rent and so the owners evict the indie stores.

True, but generally the bohemians and artists are the first ones to replace the working-class character of the neighborhood with their own, until they themselves are replaced by young urban professionals...

Comparing the wide Internet to a neighborhood with fixed space constraints is a rocky analogy to begin with. The foundation of a new city would be more appropriate, starting with a small population of intrepid explorers in a wild uncharted wilderness and growing to a massive commercial behemoth...

Facebook and the like aren't the Walmart of the web though, they're the Wholefoods and sushi bars; Craigslist would be the closer Walmart equivalent; shoving out weaker sites while still being pretty lower-income

"Polished" for search engines maybe. Bad UX is rife across most commercial sites, with intrusive ads and social trackers being the worst offenders: autoplay videos, on-scroll triggered, page re-positioning, Taboola garbage, increased load times.

All of this made the web worse, not better. "Gentrification" as it relates to neighbourhoods at least means access to better amenities. When it comes to the Web, Wikipedia offers "amenities" in the way of easily accessible, extensively cited information. Most websites on the other hand gatekeep content via email signups ("get my free ebook!"), and the content itself is basically lead gen for what ever product they're pushing.