i "almost" agree.
i daytrade YM. it's what i do. love stocks. do a little daytrading, and a lot of INVESTING (longer time frame) in stocks, but when it comes to daytrading/scalping, nothing beats YM for consistent profit taking opportunities imo.
(except for the Nikkei in the last few months, which has been unreal - but i digress)
you are right about support and resistance, but i'd take it a step further (or a step back)

and say SUPPLY and DEMAND are all that matters.
it is supply/demand inbalances that CREATE support and resistance. IOW, at levels where there is more supply than demand, that is SEEN as resistance. Sellers are more aggressive at these levels - willing to sell into the bid (and/or having preset limit orders at these levels ). That is seen on a chart (or on the tape) as resistance. It is simply a matter of sellers being more aggressive than buyers. To say there is "more buyers than sellers" as some do is in fact wrong, since for every contract sold, there is a contract bought, and vice versa. It's zero sum.
Similarly, support is "created" when demand outstrips the supply at these price levels, and buyers become more aggressive - taking the offer- which offers 'support'.
IME, when I started looking at scalping the YM as an example of exploiting inequities between supply and demand at key price levels, that is when i became profitable.
Most indicators (RSI, MACD, etc.) only tell you what happens after the fact, and imo, are almost useless for scalping, except as a general heads up, because by the time they give a signal - the move is already over.
For me, I pay attention to Volume @ Price (and.or Time @ Price - market profile), and order flow (time/sales).
In regards to the difference between the cash index, this is very useful. You will note that in extreme turning points, YM will often overshoot INDU. this is logical, because YM is an example of (mostly) short term traders actions, combined with some long time frame participants, and in the short term traders world, emotion sometimes (to put it mildly) overshoots logic.
This offers price opportunity, especially if you monitor divergences in YM vs. INDU and./or ES vs. SPX. When the price of the futures diverges too much from the cash index, then of course, that is opportunity for arbitrage trading and program trading that necessarily will bring prices back into line. It HAS to be within that narrow fair value range, or it offers zero risk arb profits, and that is why it is a constant balancing game. I just remember that futures LEAD cash (generally speaking) , not the other way around.
Supply and Demand- it's what's for dinner.
All in my humble opinion of course
