as long as the connection is established, it doesn't matter who initiated it and the network gets helped anyways.
I don't think you're uploading blocks that way.
Despite the name, you can perform both upload and download. But node which accept incoming connection is more likely to receive block from other node first before your node, since it have more connected node.
That's also my take on this subject, but wanted to verify it, so thanks.
The thing is, there must be nodes that accept inbound connections for the network to work. So, indeed accepting incoming connections helps the network, but, personally, I run two nodes, one Tor only and one with "default networking". For the latter, I didn't really bother messing with port forwarding, because I need ISP permission and I am also not very good with network configs.