I think they want to be able to pivot and add new services without having to retract how they previously labeled themselves.
For instance, Optimizely has a website A/B testing tool. They also support smartphone app A/B testing, and I think some backend/server-side testing. If smart watches or VR take off, they'll probably try to support those as well.
They also recently added automated content generation: I know they can generate product and page recommendations, and there may be other options as well.
They're a relatively young company and probably aren't ready to be typecast as "website A/B testing," in case another offering really takes off.
My main point is that it shouldn't ever be difficult for a potential customer to quickly get to that understanding, and I do believe these sites could do a far better job at quickly and clearly explaining their companies' function... just like you did.
"Meltwater's flagship product is media monitoring". "Optimizely is a website A/B testing tool". Boom.