Are those considered effective and what is the thinking behind them?
(This mostly happens with agencies/consultancies.)
It is hard to advertise a consultancy because you are generally under N.D.A. and if you really helped Company X improve margins by 35%, the last thing Company X wants is for Competitor Y to improve margins by 35%.
The dominant paradigm in software development is "gather requirements", "design something", "code it", "test it", "deploy it" and it is a pretty bad paradigm with a 2/3 failure rate in the field.
However, customers seem much more comfortable to stick to something familiar rather than follow a highly opinionated approach which is best of breed for some particular range of problems.
Many companies like that also have a sales approach which is driven by person-to-person sales and the goal of the web site is not to "knock people's socks off" but rather to not introduce any additional objections. (i.e. it is all black because the even though the head salesman is the most conventional guy you've ever met, the web designer is a lolligoth.)