Optimization of bandwidth * voltage accuracy * price, for specific purposes they are supposed to serve.
The most generic catch-all instrument would have massive BW, massive number of channels, with massively good voltaga gain and offset accuracy - but it would also be massively big, consume massive amount of power, and cost a massive sum of money.
Out of these features, DC accuracy is easiest to sacrifice, since it's the least needed in typical use cases. Multimeters are great and abundant.
The ADCs on scopes are almost always 8-bit, and the DC offset stability and gain accuracy specs of the analog frontend are not the #1 or #2 items in the optimization, even for mid-range (think $10k-ish) products.
Note that product pricing is not a linear equation. If a scope BOM cost is $1000, you can probably sell the scope for $3000, but if the BOM cost is $2000, you can't sell it for $6000, because now at $6000 you would have much fewer than half the number of customers, so less total money in, and the NRE costs need to be calculated again per projected unit sales. Sometimes this ends up to totally ridiculous sums of money, and sometimes the result is that the market doesn't want the product.