It's not about the scare factor. That's also much less frequent these days. It's about the leading personality factor.
You look at other teams, how many leaders do you see them having? Our Triplete squad was lucky to have several of those, including players who were captaining their national teams or previous clubs.
Real Madrid had that in their three year CL run with Ramos, Cristiano, Modric, Kroos, Navas, Pepe and maybe Bale plus Benzema?
You look at Manchester City, you don't see this being a factor. De Bruyne? Sure, great player, but not so confident in his leadership skills. You could argue Fernandinho and perhaps Ruben Dias, but that's about it. And this is the most hyped squad out there until PSG made this crazy summer mercato (and for this kind of effect they have Messi, Ramos, Marquinhos, Navas and maybe Verratti?)
We're not really that far behind the top teams. We have guys like Skriniar, Barella, Perisic, Dzeko, Vidal and guys like Handanovic, Kolarov and Ranocchia in the locker room. All you need is a quality coach to push them to the next level but the worrying part is that Vidal and Perisic are out, Dzeko won't have much of an effect next season and Handanovic is also probably retiring if we opt for a replacement. Not that many teams have this nowadays and we should realize it eventually. You don't need 8 or 11 or 15 leaders, but having more than a handful helps. You need a couple of great players (one in midfield and one in attack) and several soldiers (like D'Ambrosio, Darmian, Dimarco and upgrades over Gagliardini, Vecino and Sensi) and you're immediately a CL contender.