>I worked for a unicorn tech company where they determined that anyone with under 50,000 ARR was too unsophisticated to be worth offering support.

In companies where your average ARR is 500k+ and large customers are in the millions, it may not be a bad strategy.

'Good' support agents may be cheaper than programmers, but not by that much. The issues small clients have can quite often be as complicated as and eat up as much time as your larger clients depending on what the industry is.