The rule of web software has been to use a single global platform, and localize the data, language, and results. Theoretically, it should work, but, in practice, it doesn't.

When the yellow pages directories went online, they got worse. When locally developed sites, like Chowhound and Citysearch went into more cities, they started to suck. Even Craigslist, which is still good, got a lot noisier with spam.

Yet, what sucks isn't the platform, but the data. The platforms generally got better - even much better as in the case with Chowhound. But the data, content and user experience got worse.

What are some causes of decline?

1. Chaff - the amount of chaff increases as people jump from one locality to another. This was tougher on the localized sites.

2. National advertising - the national ads can afford to be placed higher, perhaps by getting a site-wide bulk rate price. These businesses prevent the local businesses from being viewed on the first page.

3. Tourism - on Yelp, a lot of out of town tourists comment. That dilutes the voices of locals.

4. Ignorance - within a local context, you expect to get more fine-grained information and advice. Most people lack that, because, it's actually hard to find. Online answerers and advice givers fall back on plan A. For example, someone may ask for a printers in Nowheresville. Someone ignorant about printing suggests the Staples in Nexttownover. A reasonable answer, but not really local information.

5. Hard to keep the world at bay - the interface isn't good at enforcing local-ness, or switching from local to "less local" for searches. Maybe the session loses its local-ness if you visit another region's pages. Maybe people from other areas come in (Tourism).

6. Errors - there are naming errors on maps. There are geolocation coordinate errors on those Google markers on some maps. People mis-locate places on the aerial maps. Databases have typos that cause buildings to be located at the wrong place. These can only be fixed manually, and it helps to have a local person who knows the area doing the data entry.