People are going to build for the tools that have strong network effects. Those Roam clones you mention have none at the present moment.
And I don't see how a Roam Research integration would be "leeching value," especially because it will eventually be possible to build paid plugins for Roam, which opens the revenue door for devs building plugins.
didn't know about docdrop, I thought it was similar to Annotate.tv but I got: "Our video annotation capability works for YouTube videos that have either human or machine-generated transcripts.". That's not a requisite on Annotate.
You need to choose a YT video that has a auto-generated transcript. About 80%+ videos do I think. Choose another one. Docdrop+Hypothesis only works on transcripts-- it's not a timecode video annotator.
Or, an open-source alternative like Zettlr, Logseq, or Athens (coming soon): https://github.com/athensresearch/athens
In general, we shouldn't let expensive paid software like Roam leech value from plugins made by volunteers!