I just stumbled over Rimworld after a long break and I just stimbled over the same issues I had long ago.
One thing was that my tribal colonies quickly get forced to evolve in technology due to raids using modern weaponry whilst I still be using clubs and bows. A thing I never really liked.
Now I was thinking, what if raid armament will be depending on colony armament? Meaning, if you primary have Neolithic weapons, enemy will have mostly neolistic weaponry aswell.
Depending on RNG they still bring some weapons above your level, meaning a uzi-wielding raid might have one charge rifle or a tribal raid have one revolver to the fight.
To work this out the basic weapon classes (neolithic, modern, advanced, mechanoid) could be used. So, if you don't have any modern weaponry in your colony, the raid generator will try to choose better quality armor and weapons in your Time period instead of switching to futuristic weaponry.
To prevent abuse I'd focus on the highest weapons of own. Meaning if you have 100 bows and 5 assault rifles, raids will use for the first 5-10 raids a assault rifle equal and the others more neolithic. This doesn't mean merceneries use bows aswell, but they get downgraded to what makes sense... revolvers or such.
As a result I imagine it to be possible to make a playthrough which only uses bows and spears, or whatevery era one likes, instead of progressing to the same high-end weapons asap.
Valid point.
Regarding tribes, i wish they were more... interesting. both to play as and against.
As they stand rn they are just a bunch of squishy balls of flesh that die by getting shot just a bit. And playing them its just a slower normal game.
The point made of "tech equality" is great, that would make possible Tribe only playthroughs, but I wish it had more to it.
They could have ways of developing better herbal meds, better ways of planting, hunting and foraging. Taming animals for war, maybe going a bit Horizon zero down, and crafting weapons out of mechanoid bits and using technology they can only explain as magic. All under the Lore of "they got so used to the Rim that they started to be part of it"
Or even, isntead of having a "tech tree" of researching, the tribes have a "Shaman/Magical/Nature powers" tree of research. And go full on "magic" stuff.
There are mods that remove high tech completely, but I don't think that's what you're asking for. I think you're asking for enemy tech progression to match your own - which would be great!
Why would you need advanced technology as tribals? Just use greatbows, and keep your colony value low, you'll be fine. Create interesting traps and chokepoints and there won't be much in the way of issues (keep combat capable tribals high however, like, at least 70% of your colony).
History shows that tribal people don't really have a choice, but modernize, if they want to survive, unless they have literally nothing of value. But in the world with slavery it's impossible. So only "sensible" way, why people with high technology wouldn't try to interfere in tribal live, is they don't know about existence of the tribe, or technology doesn't exist. So for vanilla is alright, and if you want a different experience, "there is a mod for it".
I can see your point, though. I like tribal starts, but at the point, when I finally learn, how to electricity, some of my pawns already geared up with charge rifles and use bionics.
I've used bows and pilas for a a number of years in-game without resorting to killboxes. You just have to be smart with base design and train and bread a small cheap animal. For me, I used adult Male chinchillas to run towards the enemies to distract them while I rain arrows on them. Added bonus is that chinchilla pelts are worth a fair coin. Dont think too linear about the problem. Grow and adapt. You're only limited by your imagination.