Imagine if they didn’t? No employer under 50 employees would bother getting group coverage as they could get better coverage for less via the QSEHRA route.
I suspect that a lot of people alarmed by ACA costs are really just observing that their employers were subsidizing a lot of stuff for them. That's true! Employers who give you group coverage directly are usually giving you a shadow pay raise in the background to make the numbers look better!
But for startups, the difference between the individual market and the small group market probably aren't usually that big --- as you'd expect, since a small startup isn't really aggregating much risk.
For example, the first couple years of the ACA there were N vendors providing ACA plans materially similar to small group plans. Today, most of those vendors have abandoned the individual market. So the quality of plans/carriers available to ACA purchasers vs small groups is vastly different today.
In 2015 it was the case the $500 in the individual market was roughly equivalent to $500 in the small group market. Today, $500 (or $1000) spent in the individual market won't buy you the same coverage as $500 in the small group market.