There's a perverse relationship between Master's and PhD programs in the same department.
A PhD student is an investment: they will crank out papers with the school's name on it, they will carry around the school's name for the rest of their academic career, and their projects are more likely to bring in grant money.
Master's students are shorter term, don't go into as much depth, so there's less opportunity for papers and grants. They're less likely to be in academic circles after graduation, so the school's name doesn't get promoted.
Funding for Master's and PhD students comes from the same pool, so in many cases, getting into a PhD program can be easier than a Master's program in the same department.
Masters programs are often used to print money for the department, especially for industries that have adopted the degree as an auto-salary-boosting credential. You end up with a lot of vocational students that are treating it as an investment, which is entirely counter to the aims of an academic graduate program.
The absolute worst are Masters in Education, followed by MBAs, with evening CS Masters programs trailing far behind.
A PhD student is an investment: they will crank out papers with the school's name on it, they will carry around the school's name for the rest of their academic career, and their projects are more likely to bring in grant money.
Master's students are shorter term, don't go into as much depth, so there's less opportunity for papers and grants. They're less likely to be in academic circles after graduation, so the school's name doesn't get promoted.
Funding for Master's and PhD students comes from the same pool, so in many cases, getting into a PhD program can be easier than a Master's program in the same department.