That is not how Copyleft software licenses work at all. All the AGPL gurantees is that 'Bigco' must contribute back to the community any modifications they make to the software.

I think you make a good point in this instance, so I upvoted. The follow-on discussion establishes the policy of big-cos pretty well and I don't think Alacritty much benefits from the AGPL since actual integration into other software base is unlikely (except for some of the sub-libs perhaps, but personally I feel that fundamental libraries flourish better under less-restrictive licenses anyway)