MySpace, Yahoo! Mail, eBay and probably other large scale operations were all built on PHP long before Facebook and I don’t think any of them were particularly ashamed about it.
The others I don't know, but MySpace was not a particularly big operation. Before WordPress, most sites started as PHP at some point were expected to migrate to something else, because maintainability of PHP3/4 projects was a big challenge (hence the "shame"). Facebook was the first company that simply refused to do that, and focused on improving PHP instead.