The GWWC pledge is very explicitly an EA initiative.

If you're talking about stem cell and blood donations, yes, there are many EAs who are against that for stupid reasons like "why would I spend 30 minutes donating blood when I can spend them on my very effective work", but those are also just the vocal minority and most are pretty reasonable about doing easy helpful things in addition to the main "effective" stuff. Notably for example, many EAs even do undirected kidney donations, despite other EAs arguing it's not "effective" enough.