IMO the brick wall is real on multiple fronts

1) Creative MS spend methods are largely dead. For the effort/time/risk/stress/failure that comes with this, you are literally better off buying tickets/rooms out of pocket.

2) Bonuses are weak-ish. We don't see many 75k/100k MILE or convertible currency offers anymore. Not that many. And even if you did see them, the mileage charts are positioned in ways that you can't really redeem them for even 1 round trip business class ticket to Europe. The idea of trying to churn with 2 people requires two churners, or an even larger effort by the sole-churner in the household.

3) Card companies don't want our crappy business by and large. When you subtract the manufactured spend, many of us are worthless customers. We sign up for bonuses, never use the cards after we get what we want. A great deal of us put 90% of our spend on 3 cards or less, and yet we will hold half a dozen or even a dozen+. Card companies know this. They don't want to give out their products to risky borrowers - which means churners, as churners have more than 5 pulls most often. One of the first limits you might find yourself hitting, like myself, is the Chase 5/24 rule. 5 pulls per 24 month period, and no more Sapphire/Ink/etc cards.

If you are hitting this limit, the only thing you can do is cool off for 3-6 months while your credit improves and hopefully inquiries drop off. You may start looking at obscure products like Virgin Atlantic's card, or Club Carlson, or Lufthansa's card, etc. But you start to deal with lenders like US Bank who become even less churner friendly. In addition, have you ever tried to spend 95k Virgin Atlantic points? They suck. You will find yourself spending money you otherwise wouldn't, just to use your points. You definitely don't win by doing this.