Why is Boeing being blamed for the recent 737 Max crashes?
The Ethiopian crash was in a new plane, in good weather, with multiple witnesses describing rattling noises and a smoke trail.

We can rule out weather, and pilot error seems unlikely to cause that.
The plane is so new that maintenance is not likely to be a factor either.

Blaming Boeing may not be fully justified at this point, but caution over the literally hundreds of thousands of passengers who fly on them every day is not inappropriate either.