They didn't totally break it, it's just significantly harder to play the game and get anywheres, or enjoy much of the additional content if solo. When solo you get smaller mobs, which measn lower xp, MUCH lower inf, and fewer uncommon/rare drops. I take the statemtn 'anyone can solo the game on heroic' which was told to me bya dev, and I have to laugh. They have made the game so that to really enjoy it, or get anywhere in a reasonable amount of time, you have to team. Part of it yes, is play style, but part of it is how they chose to make the game (tell me how a player is supposed to be able to get 12 MILLION inf by lv 20 without a farming bonanza or paying RL money for it) and address smaller issues with it. Due to my work schedule, I am not on at a regualr time, so I either take my chances (or used to) with pick up teams, or have to solo the game.
I've been playing CoV since launch, so believe me, I can tell you about broke toons. Before IOs were introduced, I can tell you that by level 22 you haven't earned a third of what it takes to buy a full set of SOs (about 1.5mil) via regular missions. (Because that's what I did, several times.)
So if SOs cost about 1.5mil @22, why would you need 12 million inf on a level 20? (On the average toon, you haven't earned 1.5mil total inf in defeats/mish XP until your late 20s.) And actually, the solo player will earn more inf from mobs than a group, while groups will earn more XP. (Wasn't there a post some time back on these boards about someone making 36million inf in one level while street sweeping Founders for one level in their 30s?) Still, you don't need to farm, or market PvP to make good cash; just craft and sell the drops you don't need, or sell salvage for profit. It's not hard or time consuming; 5-10 minutes of your time each play session and you have decent extra cash. Certainly enough to fund an SO or common IO build. And only fools pay for inf with cash.
Now, I will totally agree that solo the lowbie game (from about 6-22) takes forever. The XP-gain to effective fighter ratio is far skewed against your favor, plus Mercy blows and I'm always ever-so-happy to be the heck outta there. I tend to make things harder on myself by not bothering to buy enhancements. I will often craft and slot what drops I get that are useful, but otherwise everything gets vendored or put on the market.
However, as a player since before CoV launch, I can tell you they've made the trip up SO much easier. Not just with the XP Curve smoothing, but at the very least, common IOs at low levels give you consistency in effectiveness, even when used very sparingly. (Remember being stuck in your mid-late 30s for ages, literally? The XP curve was so off you could level a new toon 1-30 in the same time it would take to get from 36-40.)
If you're under the misunderstanding that 'anyone can solo this game' means 'soloers are as effective/quick as teams' I can see why you'd be put off. But solo doesn't always equal fast. I see many players complaining having a hard time finding teams, but are completely unwilling to form one themself. Hosting teams is really not difficult; at the very least, you get a handful of relative level and do newspaper/radio missions in zone. Pick a mish, set a mish, people go. What's the big deal?