To an extent yes. Just by the fact that more people are posting actively, they must be making page impressions and looking around. More importantly, the sheer volume of content (however mindnumbing) does boost the sites ranking on search engines.


I would say more so judging from the site advertising stats page https://bitcointalk.org/adrotate.php?adstats
Total page impressions are usually ~5x page impressions from logged in users. But the unanswerable question is how much of that traffic is driven by searches would reduce.


The last round of advertising pulled in 2.4BTC https://bitcointalk.org/index.php?topic=3006864.20
It is an auction and it is really a matter of opinion/speculation as to how that would be affected by reducing spam. Would the bidders pay less if there was less traffic?


Back to the closing threads issue. I don't think it would reduce spam as new threads will simply replace them. Many of these threads are actually opened by account farmers for the purpose of answering from their alts. What it would do is stop annoying anyone that replied early in the thread from constantly seeing them pop up in their unread replies page.