I started an alt account a little over 3 weeks ago.
1) Yes, the Arena is way tougher than before. So it is harder to progress. BUT, the majority of peoples problems is focusing on the other easy missions. You will get stuck in the missions again and again, and it gets worse. It's not going to change.
2) You need to farm and rank up 6*s. You just have to. Most that struggle have 1 60, and 10+ 50s. Well this is why you suck at this game. You already see all the teams in silver 2/3 have at least 3 60s for the most part so guess what my next step is...
3) I have 40 Spirithost 50 Warmaiden 60 Jinglehunter 60 Kael. I need to rank up WM to 60 probably, make my team faster since I can't pull Apothecary :(
4) I have 1 GH to level 4, 400 more medals will take a while to have 2 for the next mission...oh well. I'm going to farm, improve the gear on my current arena team and hope for some shard luck. Also, I could fuse justicar in a couple days so I'll have the potions ready to go and do my last little bit of leveling as well.
5) There is no rush with these missions. The Arena missions aren't holding you back. Things holding people back 1) lack of farming for 6* 2) wasting gems on refreshes/refills or to get an atk% of gear 3) spreading resources too thin (FOCUS only on core heroes)
6) If you can't get out of bronze/silver after 100 days, you should start over and listen to the advice of PlayerJ, Daering, Ethan, Valdys and others the second time around.
I do think because the overall caliber of teams has obviously increased over time they should do something to help. The easiest would be to include a token refill bag with every levelup to 60 sent to the inbox with 99 day expiration. Helping newb accounts makes sense as they will never catch up completely. Doing a 10x from blue shards on Apo would also be good.