Logically that makes sense. Not here and for a beginner as he stated.
These players have 100's of games under their belt, even at 1200-1300 and your new to chess you will beat badly. Mentally that will not make it fun and leave frustration. Start off and learn the basics then expand. Must walk before you run.
Yes speed chess is helpful, even for beginners; it forces your brain to work more quickly - you focus more intently, which is a key to winning chess. Definitely do all different speeds
"Haste makes waste"
learn to make by taking your time first
speedy blunderer vs speed good moves
:
Having fun is not a waste of time.
The harm or good it will do to you will depend on how you play said formats. If you are playing to always win on time and play garbage to see if you can mistify your oponent then your long game will suffer. If in turn you play good openings and try to find the best move always and play good solid chess then it will help your growth as a chess player.
I personally have found people to be quite negative when it comes to blitz. I don't live close to a chess coach or anyone my level, and I can scarcely get to tournaments twice a year. I think online chess is great for long deep calculation as said previously, but you need more than that.
Play 5|0, 10|5, and 15|10 games, as well as online chess. They all teach different, but important aspects to the game. Make sure that while you play these, and online chess that you play at the pace of the time control.
Where people run into trouble is when they play only 5 minute or only 10|5 games. They become comfortable at that pace. Being comfortable is not conducive to winning outside your comfort zone.