Good post. During the height of that meme, I must've come up with at least 30 different arguments against the idea that Spurs are better without Kane. As part of the "theory", if you can even call it that, relies on previous short spells without Kane during which the team did okay, I thought about the psychological effects on both the Spurs team (seems like everyone steps it up a gear for their own various reasons: understanding the need, wanting to prove themselves etc.) and on rival teams (thinking basically the same as you).Another issue when comparing With Kane to Without Kane, is that PL opponents know how we play with him and have inevitably worked out a kind of optimal defence. When he's out, they need to work out how we're going to play (as do we!). So for a period after he gets injured, I would argue that the forced shift in our tactics makes our opponents weaker, but this is not a sustainable shift because they will figure us out.
Worrying now is that without him I think we just look poor, although there are some glimmers of hope in how the new guys are coming on.
I eventually concluded that, in the short term, the Sons and Deles etc. would and were benefiting from increased space as the opponents' defenders had less directly intimate familiarity with Son etc. and would not be instructed to and/or know how to double/triple up effectively on any one of the Spurs attackers (a pertinent question for the managers would be "which one?") as they would on Kane. But just as Kane had to overcome the problem of being double marked all over the pitch in his second season - a test that has felled so many one-season wonders - Son and Dele etc. would have to overcome the same problem before long (and it definitely wouldn't take a season).
Even though if you just watch a typical XI Spurs match, it looks superficially like the team could do the same shit without Kane (which absolutely fed the meme), it was clear, on a deeper level, that this wasn't the case. The space the other attackers receive from two or three runners going with Kane when he peels off would not only be lost but the remaining attackers would actually have to be able to deal with that extra attention themselves. And that's partly why I think Kane is still a little underrated or at least underappreciated: he makes that stuff look like a routine part of the game, to the extent that it tricked tons of football fans into thinking that Spurs would do great without him.
On that basis, I predicted that nobody else in the squad would have the same combination of attributes and skills needed to fill in fully for Kane in the long-term -- and that seems to be true. I did get a kick out of a few (mostly Korean) lads in that "best player" thread saying that Son would outperform Kane as a drop-in CF replacement whereas Kane would be a trash winger (the latter is at least true, I guess).