Most software I use is not built and packaged by the person who wrote it.

Vivaldi is however, as large parts of it are proprietary.

Ah yes, parent was saying that he hopes you'll build yourself if source is released in response to grandparent asking for sourcecode. So if it'd go open-source I still wouldn't be building it myself.

If its open source then packagers will do the job for me

They could support reproducible builds, then any third party could verify the binary they distribute hasn't been monkeyed with.