well actually, there's quite a lot of skills involved in 1a on top of what you mentioned.

DR camping - well, this one takes time. so I don't consider it a skill but Xin thinks otherwise cuz there're people who can just click that 0.1 second faster than you EVERY single time.

land trading - it's easy to land trade, but it's difficult to excel at it. Most landtraders suck in 1a. LaF did it once and we showed everyone who's the boss. It involves: choosing the right target; hitting the people of the right size; what NW do I get to maximize gains; whether you initiate the hit or you get hit first; do you save this target for a 2nd hit later on or do I landtrade for the 2nd time now etc. There's alot of considerations that go into it. Good landtrading is a skill.

market play - this is key in 1a. market is a lot bigger in 1a compared to the solo servers. Volatility is there and there's opportunities for arbitrage in all volatile markets. deciding when to destock; deciding when to stop cycling your bushels etc. This is a skill.

warring in 1a - do you kill with GS? do you kill with BR? how fast do you kill? Do you wait for type 1 fast DR to expire before continuing (of course, this has been removed) etc? It takes skill to maximize damage with limited turns.

heh, so don't write off 1a just yet. it's a whole different arena altogether that requires very different skill sets.

I would say most people who can consistently finish top10 in 1a can do well in solo servers, but not the other way round.