The last time I cold-emailed someone was back in 2021 when I had issues with uboot. Some software doesn't make it easy to file bug reports, and this one chap was working on the same board I had, so I felt like I had nothing else to lose. Thankfully they were nice, actually knew what the problem was, and had a fix in that same week.

The big one is the fact that you will likely be ignored by a large host of them. Even with modern spam filters, a lot of unsolicited messages are simply a waste of packets. Odds are, even your useful, inquisitive message will be buried under the more disingenuous messages, especially in an age of LLMs. Trying to get in contact with anyone that already has a large audience can be discouraging.