Rogues are woefully behind the curve in games with feats enabled unless they reliably get in that off-turn SA, since there is no feat that increases Rogue DPS like the -5/+10 feats.
Well, feats are optional, so not too serious an issue, really. Balance around the standard game would have to be the priority.
You can call this "hyperbolic CharOp nonsense" all you want
Oh, there's nothing non-sensical about analyzing how the rules actually work, it's just that, in a game that could not have been balanced well, given it's other, much-higher-priority goals, if we do want balance, we should start with the game's standard form, the no-feats, no-MCing campaign, that averages 6-8 encounters & 2-3 short rests per adventuring day and doesn't use magic items. That's the closest we can expect to come as a balanced starting point, and the best starting point of a DM interested in imposing any sort of class balance.
most games don’t use feats, first of all.
Feats are optional, not part of the standard game, as presented. It seem like a
lot games use them, but whether it's some, or many, or few makes no difference to their status as an opt-in tool for the DM.
And survey feedback and play stats seem to point to broad player satisfaction with the Rogue.
Or broad popularity of the archetypes it models.
It’s also unnecessary, and not part of the balance assumptions of the class.
Indeed, the rogue is easily the class least dependent on limited resources, and most dependent on situations, to maximize DPR. A good, diverse, 6-8 encounter day has a lot more to do with how it'll balance, DPR-wise, with an Action-Surging fighter or Smiting Paladin or the like.
it doesn't specify allies only SOOOOOOOO......
Plus Protection and Intercept sound specific in nature: one more designed around guarding allies and the other more tactically defensive in combat.
I don't think 5e has a specific jargon meaning of allies, so it uses phrasing like that found in protection style "..targets a creature other than you..." while Intercept omits part of that phrasing. Both are natural language, the presence of one strongly suggests one possible interpretation of the other, yet if the game were truly exception-based we wouldn't be expected to rule by analogy or precedent like that.
So, maybe an oversight in the phrasing (my guess), maybe just natural language not always being identical when saying the same thing at different times (lacking the precision of specialized jargon), or maybe intercept phrasing is less explicit precisely because it's an optional rule DMs may wish to implement in subtly different ways.
Whichever, it's up to the DM to make a ruling, and incumbent on players to understand & accept that it's the Ruling, not the Rule, that counts.