Actually, it's because the Leafs have multiple good RFA players....with Marner, Kapanen, and Johnsson yet to sign, offer sheet speculation is clearly warranted.
Tampa I'll give you....but Tampa's fans (and likely management) have proposed that multiple, quality players are likely to be moved....guys like JT Miller and even Yanni Gourde have been proposed as trade options. These are players with term on realistic contracts. With the proposed cap increase and that additional salary moving out, there's a little less of an issue.
Winnipeg is similar in one way (to the Leafs) but dissimilar in another. They are alike in the fact that they've got 3 high-profile RFAs to sign (Laine, Conner, and Trouba). They are dissimilar in the fact that the Jets have almost $24 million in cap space. Sure that gets eaten up pretty quickly should 2 of those 3 guys get Matthews-like contracts. Yet, again, there are multiple proposals and rumors about Trouba being moved....even Conner's been mentioned....and lately, because of Laine's uninspired play and even worse results, his name has surfaced.
The Leafs are $10 million under next year's proposed salary cap and one of their RFAs is being touted as chewing up that remainder.
The threads on HF aren't because you're "the Leafs"; it's because your cap situation and roster situation warrant a lot of speculation.