Whatsapp had 55 employees and 1.5b monthly users when they got acquired by FB. I very much doubt that the product is fundamentally better now that they are part of a company that has tens of thousands of employees. Same could be said about Instagram I guess?
It's the tyrrany of the rocket equation. Each dollar of revenue costs more than the last, and the money keeps getting spent until they are paying $0.999999 for earn $1
