Why carry a multi tool? In 20 years of road riding I can count on one hand the number of times I've needed to adjust something with a tool. Take a look at your bike and what you would legitimately need assuming the bike is maintained correctly and a situation you could repair yourself with only the need to get home. For tools I carry (outside of flat repair):
-short 5mm hex. fits just about everything on the bike including shifter hoods if you crash or the quite hidden saddle rail bolts. Multi tools struggle there.
-short 4mm hex. Cable pinch bolts on my kit are 4s. My bike only has 6mm bolts on the back of the 5mm ring bolts so no need for a 6.
-T25 add on bit for the 4mm hex. Comes with the Zipp stem I use, they even sell them.
an oring holds the two keys together, the bit is magnetic.
Never felt the need for a chain tool on the road. Crank comes loose? Multi tool isn't enough leverage to get it tight enough but fall back to maintained correctly as the answer there.
Of course there will come a day when the phone is the way to get home but I've been resourceful enough to solve any issue so far. If an issue needs more than the very basics and some smarts then calling someone is likely a better plan.
Carrying a multi tool for me ended many years ago when not being able to reach the brake pad bolt after a broken spoke on a CX woods ride. Even when I used to guide MTB trips the carry was separate tools rather than a multi, a Leatherman excepted. Separate tools are cheaper, lighter and work better than multis.
most of the allen keys on my multi tool are made out of soft cheese (crank bros one), but the chain tool and with built in spoke key has saved me and friends on numerous occasions, I consider it an invaluable piece of kit, the slight added weight doesn't bother me.
I've also used short the 8mm allen key to tighten up cranks (more other peoples than my own) adequately to continue on a ride, I found you can apply more pressure by keeping your gloves on. I have been looking at new multi tools, but the chain tool on the cranks bros is really decent, never failed me and had the thing about 10 years.
I'm definitely don't take a weenie approach to what I carry, I carry a spare tube, levers, a patch kit, a pressure drive, some proper allen keys and the multi tool, but with that array I'm pretty self sufficient... I need to be, my GF wouldn't be driving out into the countryside to pick me up!