Ive now got two alts which are slighty trailing behind my main. I wouldn't say artifacts on alts are a hinderance at all
You level them, log in every x amount of days - do the research - Go catch up.
Now second specs, honestly I haven't even switched specs once, not even for legacy raids or soloing. I think it's a good thing spec switching isn't as big as it was. For the first time in years I see people asking for help, working on their specs properly and everything