Well, the game *does* present it as a path though, doesn't it? The choice between siding with the goblins and siding with the grove is pretty binary, and is treated as a major story milestone-it sets you on the next leg of your journey, as well as being a milestone for any romances you might be interested in. And yet this binary choice is *heavily* weighted in favor of helping the grove. The multitude of 'red flags' have been mentioned. From the first True soul we meet (edowin), you learn that the absolute's forces want you, specifically *you*....dead. It's also made abundantly clear early on that none of the true souls know about their 'condition' and thus couldn't give you any real insight on how to cure it when you talk to any of the three leaders in the goblin camp. Gut in particular will nearly kill you, can't be reasoned with, give you any help or guidance to your next goal (unlike Nettie, her counterpart in the grove). It's very clearly foreshadowed that getting the brand or using the tadpole powers is a bad idea long-term, and 'Daisy' is pretty obviously bad news. Basically the best you can get in EA is 'go to moonrise towers and hope things work out, even though your cover is blown after the raid on the grove.
When I have tried playing evil, I try to RP it as taking down the cult from the inside, sabotaging it and subverting its assets. But it really isn't great that way. The only 'allies' you can get so far are Minthara and Nere, who are mutually exclusive. Minthara will even tell you that she can't resist the Absolute if you ask her. There are not great options, to say the least. Meanwhile, directly fighting the absolute showers you with allies like the Myconids, Gnomes, Halsin, etc.... Notably those first two require Nere's death, which means you trade essentially three allies (Minthara, Myconids, Gnomes+Wroot) for Nere.
That's the sort of trend that holds true just about everywhere in terms of content playing an evil character in BG III. Go to the goblin camp and talk around. How many side quests did you pick up? Did you get any major ones like the Shadow Druid investigation? Any npcs who promise to meet you later on in the game so you can check in on your favorite ones? How about quest rewards? Workign for the druids and tieflings gives you all sorts of great stuff. Stuff you can't get by killing them. Unlike with the Absolute cultists+goblins, who give you nothing for helping them but are loaded down with extremely desirable magical items (again, Minthara and Nere in particular have some great stuff) How many of those npcs mentioned earlier will join you as camp followers? (none).
Etc Etc.
There are warning 'flags' everywhere that the absolute can't really help you. They give you no loot, no rewards. You don't gain any allies, no sidequests to speak of, etc. Arguably you sabotage yourself, since you lose companions and romance options, kill off your most promising leads (Halsin etc) while gaining no real allies to speak of and it's revealed that your cover is blown right after the goblin party. Hell, even Volo tells you he's going to go around telling everyone that you are an evil murderer. Siding with the goblins is just screwing yourself over as they are written right now, and IMO that's more than a fair target of criticism.
