Some really great vids linked in the OP -- thoroughly recommend people have a look at them, they explain the whole brush vs hitting thing very succinctly.
As for the whole slow vs fast equipment thing for beginners, the issue that cuts the Gordian knot here is control.
Either you can control the ball enough to consistently put it exactly where you want on the table, using your equipment or you can't. I find that most often, if a beginner can't place the ball where they want on the table, most often their set up is too fast.
On some occasions I have seen beginners improve by switching to slightly faster equipment -- however, in such cases --more often than not -- the problem is not a lack of equipment speed, but rather improper technique creating a lack of speed. Proper technique creates it's own speed, and makes having slightly faster equipment slightly redundant.
The biggest issue I find with handing fast equipment to beginners, is that it compromises the development of their sense of touch, and as a result they don't really gain much control over match tempo.
It's far harder for a beginner to slow down fast equipment, than it is for them to speed up slow equipment. Being able to vary the playing speed of the game on demand, in order to disrupt your opponents sense of rhythm, throw off their timing of the ball during stroke play, and thereby increase their unforced error rate, is all a big part of modern tactics and strategy.
Yes extra speed and spin are great, and we all love to execute a great passing shot. But at higher levels it'sa lot more difficult to blast past your opponent with pure speed and shot quality alone. You also need a real sense of guile and finesse with your stroke play and spin variation on top of that, to win matches at the higher levels. This requires the ability to vary tempo, and play a slow patient game on occasion that employs not just power and spin, but also genuine deception at the same time.
When beginners pick up fast equipment, they can fall in love with all that extra hitting power and spin, and forget about the nuances of technique, placement, variation, deception and disruption.
The simple truth is, it is usually far easier to learn guile and nuance with slower equipment. Ideally a beginner should learn guile, finesse, deftness of touch and deceitful play first, and enormous hitting power second. The former requires lots of playing within yourself and mastering control of the ball, before learning how to put the ball away.
Yes, sometimes having greater hitting power wins you matches... But it's very, very rare nowadays for hitting power on its own to get you anywhere substantial in terms of building your rankings.
Smashing the ball first doesn't win you a match.
Getting your opponent horribly out of position first, or having them completely misread your spin, and THEN plowing past them with a smash, is far more effective
Guile, finesse, and deception are what create the openings for hitting power and speed to do their job, and win you the point. Hitting winners is only 2% of the game -- engineering a opening for a winning shots is the other 98%.
But you can't do either of these, without control.
Ball control always comes first, regardless of the playing level, or the style of play -- spin, speed and power without control or nuanced placement means you're literally just swinging and missing all the time.