I still say that my statement is correct. I said "over time" meaning that if somebody has let those things pile up for a long period, years maybe, removing them can improve boot times and even access times for the things you do have installed. Will it make a difference if you regularly clean it out without letting things build up? Probably not, but not letting it get to the point where it does slow things down is the whole point here. That article also gives an example how only a registry clean fixed problems with being able to connect after changing ISP's so left over things can break other things.
I totally agree about Puran defrag though. I was using Auslogics , which is excellent in it's own right, but Puran seems to do a better job and will defragment everything on the drive. I have switched to it.