This has come up before and is provably false with a few exceptions
My experience is the train is 3-4x quicker 95% of the time except for 2-3 block distances. Waiting 10 minutes vs a 5 minute walk makes little sense.
The streetcar is dramatically quicker at all times except rush hour, during a major event or at peak city market time. Crazy city market traffic absolutely changes the equation.
The train moves so fast that one time on a Sunday I hopped on the train at 19th, rode it NB to 16th, got off and walked to 12th via Baltimore (6 blocks) and got on and rode back to 19th. The train made it from 16th, all the way to the city market and back and I got on the same train again.
I one time got off one train at 12th, the next was behind us pulling into 7th. I made it to 11th when it passed me. It did 4 blocks to my 1 block.
If it sits at every single light for 30 seconds (it never does) that's a total travel time of the 2.2 miles of 6 minutes. Add 30 seconds per stop and that's 12 minutes total travel time.
Average fit walking speed is about 3mph. If you hit every crosswalk as go (you won't) you will take about 40 minutes to walk the streetcar line.
And that's if you're fit. Someone who's carrying groceries, walking with a small child or other impact to mobility could take an hour. Especially going NB up the crossroads hill.