Missing from that tutorial are:
1. Raising that you get more monarch points the higher the influence. Particularly if influence hits 70%.
2. Raising that it's very useful to re-assign land: as your empire grows in size, and loyalty permitting, remove land from Estates and give them newly conquered land, so as to work around high autonomy.
3. A warning about Estate-related events when influence reaches 70%.
To illustrate the latter point: The Social mobility event can kick in if Burghers have 70% influence, and let you pick between +10% influence for Burghers (putting you in disaster territory) and -20% loyalty for Nobles and Clergy; or -10% Burgher influence, -20% Burgher loyalty, -15% army and navy tradition, and -75 admin points.
Point being, there are two ways to deal with Estates:
1. Keep them happy and mostly ignore them unless you need an advisor or some quick monarch points.
2. Actively micromanage them so as to milk 100+ monarch points from each every 20 years.
The first approach is simpler and carries very little risk: basically assign (or re-assign) land as relevant. Recruit advisors etc. from time to time. And grab monarch points (and ducats) when the situation allows it (that is, 60+% loyalty). The second approach requires much more regular monitoring of what's going on.
Lastly, be wary that there's a bug in the interface, whereby an estate's influence advertised in the Estates menu (or in Estate events) reflects what it was at the beginning of the month rather than what it currently is. An event may therefor give the impression you're about to take a good decision that turns out to be terrible when the Influence is higher or lower than it actually is. To play it safe, pause and double check the Estate menu before picking any event-related option that will increase an Estate's influence, and work out the total manually, else you may find yourself in 70% influence territory.