Why does the account matter more than the reply?
Every guide about finding customers on Reddit — ours included — arrives at the same place: you found the thread, now write something useful. It quietly assumes the person writing has an account that Reddit and its moderators will let speak, and a great many first attempts fail there rather than at the writing.
The account is the asset — the one part of a Reddit strategy that cannot be bought, delegated, automated or hurried. A perfect reply from a three-day-old account is a reply almost nobody sees, and the failures all look identical from your side: a posting gate, a community spam filter, a reputation filter, Crowd Control and one line in a moderator's AutoModerator config produce the same silence, and none of them notifies you.

Comments are the realistic path, and the better one
A useful comment in someone else's thread is the lowest-friction contribution on Reddit: no title, no link, no permission, and judged only on whether it helped the person who asked — which is the exact shape of every reply you will eventually want to write about your own product. The practice is the goal, rehearsed without the stakes.
Reddit's own advice to somebody whose post vanished is a comment instruction: “even earning a small amount of karma by commenting on another post within a community, can help you get past the filter.” Community karma — earned in that subreddit rather than sitewide — is what several filters read, and it can only be earned in the room you want to be in.