DREAD's rules: Level Cap at lvl 8

Level Cap at lvl 8

PLATE V BAS-RELIEFS AT AN ENTRANCE TO A SMALL TEMPLE (NIMROUD)

Why limit your players to Level 8?

First the TLDR-answer: 

• sweet spot of 5E
• less important save rolls
• no "Fast-travel"-teleportation
• mono-classing is a better option
• main attribute 20 reachable

A bit more detailed:

• In my experience, reaching lvl 11 in D&D5 changes everything, and it means that the characters suddenly reach a much higher level of power.
• In my opinion, it is much more difficult to offer the players a good challenge without going much over the top in the plot after level 10.
• The Tier 2 of D&D5 (lvl 6-10) is in my opinion the sweet spot of the edition: Challenges are possible, even with a lot of low level enemies, but it is possible to estimate the risks of such an encounter.
• My practical observation is that after that, the outcome of encounters seems to become much more random, since saves then become so much more important and decisive. If you fail your first save in the round of combat, then you're out. If more than half the party fails the save, then the encounter is doomed to be mortal (sometimes even for the whole party). Since i'm a very unfortunate player, I tend to sit more than half of the time at the table side without being able to do anything. And that's a fun killer, in my opinion.
• Capping the level at 8 doesn't completely takes saves out of the equation, but makes building encounters without having to rely on saves much easier to build. And if the opponent is a spellslinger, the max difficulty to resist his spells should be around 16 (still high, but doable).
• So why not capping at level 10 ? - that wouldn't change anything for the spell saves... My main reason is lvl 5 spells, particularly "circle of teleportation". I don't want travel to be instantaneous over long ranges (1] I want the travel element of the game to stay something challenging and 2] I don't want to think about the societal and economical consequences of the existence of such a magical wonder)
• Level 8 also means the second ability increase for mono-class characters or balanced 2-class characters, and this is the opportunity to reach 20 in your main attribute in my campaigns (I either use shared randomized attribute pools [numbers are random, but all players use the same pool of random numbers], or point buy with 16 as highest limit). I feel this "natural customization limit" of the characters needs to be reached. After that, only magic and alchemy can help your alter ego getting better.

Does that make sense to you?

Edit: apparently it didn't completly fit and some of your remarks made me modify the cap level to 9:
DREAD's rules: on second thoughts, Level Cap at lvl 9