Beyond a certain size corporations shouldn't be allowed to acquire companies.
In fact, strong (~free) capital markets in which acquisitions happen frequently allow for more efficient (~optimal) allocation of resources over the long run, even if any single acquisition may not be locally optimal
I argue that's an opinion.
I also argue that allowing for does not mean ensures.
I also argue that, in practice, acquisitions happening freely typically result in "more efficient" allocation of humans to the detriment of those humans. Also, "more efficient" allocation of resources often increases the cost of those resources to other humans consuming those resources.
So yes, it's a valid opinion but in practice the stated results are infrequently achieved and come with significant costs that aren't accounted for in a purely free market situation.
IBM is clearly running on fumes by now. Extending its life by pulling down more small companies with them only makes things worse for everyone.
Like all things, there is much more nuance than "big corporation bad."
You're arguing for a draconian regulatory response (it sounds like) to what should be a market issue.