Every platform comparison judges how far your own post travels. There is a second way to grow that most of them ignore: replying to other people. It is the cheapest cold-start lever there is, it needs no audience to begin with, and only two platforms really have it. This is one section of a larger piece; the full comparison table puts all nine channels side by side.
The lever X and LinkedIn have that YouTube and Instagram do not: you can grow by replying to other people, not only by posting
Every platform above was judged on how far your own post travels. But there is a second way to grow that the comparison so far has ignored, and it changes the picture for X in particular: on some platforms you can grow by replying to other people, not only by posting your own content. This is the one genuine edge X and LinkedIn hold over the video platforms, and it is worth pulling out on its own:
- On X, the reply is the real growth engine for a small account. A thoughtful reply to a large account's post can be seen by that account's whole audience, and a reader who likes it is one tap from your profile and a follow. This is how most followed-from-nothing X accounts were actually built, no existing audience required, you go where the audience already is. And it ties straight back to the paywall: the "boost" you buy with Premium is literally reply prioritisation, so paying is really paying to have your replies surface higher in crowded threads. The reply lever and the pay-to-reach story are the same story.
- On LinkedIn, commenting is a primary growth input, not a nicety. A sharp comment on a big post in your niche puts you in front of that author's network and their most engaged readers, and drives profile visits the same way. Serious LinkedIn growth advice budgets comment time roughly equal to posting time, which is why the LinkedIn breakdown tells you to do the same.
- Video platforms mostly do not have this. On YouTube, commenting on someone else's video does almost nothing for your channel: the comment does not distribute you, and there is no follow path out of it. On Instagram, comments on big accounts get little visibility and carry no clickable link, so the return is tiny. The growth unit there is the post itself, not your presence in someone else's thread.
- The in-between cases. TikTok is partly there: a top comment on a viral video can itself rack up thousands of views and send curious people to your profile, but it is luck-of-the-thread, not a reliable channel. A Facebook Group looks similar because participating in discussions is the whole mechanic of a Group, but the lever is weaker than it appears: in someone else's group you reply as a person, not as a brand (you cannot act as a Group, and Groups do not offer the Page-style identity), and even a comment made as your own Page carries no prominent "follow this brand" button the way an X reply does. So replying in a Group builds in-group reputation and DMs, not a transferable brand following. It is useful, but it does not compound an owned audience the way an X or LinkedIn reply can.
- Why this genuinely changes the calculus. Replying is low-effort, needs no audience to begin, and compounds real relationships, so it is the cheapest cold-start lever there is. It is the single strongest argument for X despite everything negative above: you do not have to wait for your own throttled posts to be discovered, you can borrow other people's audiences one good reply at a time. For a B2B or build-in-public account, that lever plus a Premium subscription to surface your replies is a legitimate, if slow, way in.
Same colour coding as the other tables, and click any column header to sort (best first; click again to reverse).
| Platform | Does your reply or comment reach other people? | Path to a follow from it? | As a growth lever |
|---|---|---|---|
 X (Twitter) | Yes, into the whole thread's audience | Strong, one tap to your profile | Strong, stronger still if Premium boosts your replies |
 LinkedIn | Yes, to the author's network and readers | Strong, profile-led | Strong, a primary growth input |
 Facebook Group | Yes, discussion is the mechanic | Weak, you reply as a person, not a brand | In-group only, reputation, not brand followers |
 TikTok | Sometimes, top comments on viral posts | Possible, profile tap | Hit and miss, thread-dependent |
 Instagram | Barely, low comment visibility | Weak, no clickable path | Weak |
 YouTube | No, comments do not distribute you | None to speak of | Negligible |
| Facebook Page | No | None | Negligible |