Unfettered opinion can be a dangerous thing. It is the plague that has caused a great deal of damage in the Church in the past 50 years. Opinion often becomes an occasion for the deadly sin of pride. Not infrequently these sites bring to mind St. Paul's words in his letter to the Romans:
Now I beseech you, brethren, to mark them who make dissensions and offences contrary to the doctrine which you have learned, and avoid them. For they that are such, serve not Christ our Lord, but their own belly; and by pleasing speeches and good words, seduce the hearts of the innocent.
Romans 16:17-18, Douay-Rheims Translation
Out of aversion to detraction, I won't mention any sites by name. However, on one very popular mainstream Catholic site, Traditionalists are routinely verbally flogged, tarred, feathered and treated with an extreme lack of respect (particularly by the moderators.) Half-truths and outright lies about the SSPX in particular and Traditionalists generally are permitted with impunity. With dread and shivers I recall the Protestant persecutions of Elizabethan England whenever I visit that site. On another--ostensibly a Traditionalist Catholic forum--the moderators are slow to punish any infraction of their own rules. Free reign is given to open blasphemy on one recent thread, genuine anti-Semitic hostility on another. (One is uneasily reminded of the lax disciplinary measures frequently attributed to post-Vatican II bishops and popes.)
Overall, do these discussion forums strengthen the faith of those who frequent them? Ultimately, I don't know. But for Advent, I have decided to avoid these places. Who knows? I might find it so beneficial that I eschew them permanently.