I think the reason to buy a struggling company is simply to get access to its IP (patents mainly) and customers, not to take over its operations. If it's struggling, it was already doing things badly and probably can't be saved.

Usually, when I see tech companies purchased, it's because the company wasn't struggling: it was doing quite well, but was small, so a much larger company bought it up in an acquisition to add its capabilities to their own, like the Borg. The big company gets IP, customers, revenue, and an already-working business, while the founders get a big payout.