I think it is accepted wisdom for small SaaS startups, not a universal knowledge. For a company like Optimizely with the established user base, possibly it is smarter to go after 100 enterprise customers, rather than 10,000 mixed ones.

I personally strongly disagree with such tactics and I think this might lead to the company collapse in far future. By cutting out small users, you are wiping out testers, that pay to use your product and provide a valuable feedback. Instead of cutting out the smallest customers, they should optimize their offering, so that small users are being served completely automatically, hands-off, with only email support provided.