I think the term 'LRM boat' warrants a great deal of caution, particularly in terms of what the person saying/typing it actually means.
Every time I hear or read the term 'LRM boat', I think of the
http://www.sarna.net/wiki/Viking or something similar- a 'mech that might have a couple of very small backup weapons but has virtually all of its equipment weight dedicated to LRMs.
'Mechs like this are essentially wasteful in MWO. Dedicating yourself to LRMs to this degree is not only exceptionally dangerous if you happen to get jumped, but also hazardous for your team's ability to win. I cannot count the number of times the last 'mech on the field has been a Hunchback, Stalker, Timber Wolf, or Mad Dog with only small lasers for close combat (one energy hardpoint filled with TAG just to reduce the weapons load even further). I've even seen such insanity as an Atlas whose entire weapons loadout was two medium lasers and an LRM-20.
The result of a build like this is a
completely ally-dependent 'mech, which is a bad thing- it means your allies cannot depend on you in turn. It's a team game and your allies should be able to look to you for support that you are capable of independently.
I'm even wary of such things as LRM assaults with four medium lasers or less overall weapons power for backup- assault 'mechs are too slow to acquire good firing angles all that often in many cases, which means you need to be able to pump in a vital amount of damage while you have your one shot.
It's because of this that I only have two 'mechs that really qualifies as an LRM boat by the definition I recognize. I used to have three or four, but everything that was an LRM boat simply flat-out
got better when I diverted some tonnage from launcher size and/or ammo to put it into secondary weapons. I rarely if ever even take out my remaining LRM boats (A Shadow Hawk 2D2 and a Catapult C4), and the smaller one is even only still an LRM boat because I'm a terrible match for Shadow Hawks and can't be bothered to try and find something else to try with it that I haven't already failed to do well with the variant. The C4 only qualifies because it only has the two energy hardpoints anyways.
What I'm really trying to get at here is that some people hear or read 'LRM Boat' and think of things like the Viking, and others write or say 'LRM Boat' and think of a Stalker with two LRM-10s, two LRM-5s, four medium lasers, and an ER large laser. Which often results in new players thinking that it's a good idea to take just LRMs and/or that 'secondary weaponry' doesn't need to be enough to score serious damage on its own.
I think it's a term that really needs to be standardized amongst players just for the sake of making sure everyone means the same thing- particularly with the degree to which opinions vary on the value of LRMs as a whole.
In other notes, I don't think large amounts of LRMs are necessary to make the weapons system valuable, nevermind viable. Claiming that LRMs should only be boated is essentially a less drastic version of the 'LRMs are worthless' opinion, because all it's doing is tacking on a phrase; 'LRMs are worthless unless you bring a whole lot of them and dedicate the 'mech to them above all else'.
On assault 'mechs and slower heavies, LRMs are exceptionally useful for allowing the pilot to have a 'footprint' on the battlefield even when they cannot connect with direct fire weapons contributing further damage to allies' targets with indirect fire. On lighter 'mechs, they allow what would otherwise be just a spotter to contribute fire as well, particularly if other allies have LRMs as well- a 'mech under LRM fire is unlikely to be able to pick out that 5 out of every 25 or so LRMs are coming from a different direction so they can go hunt down the spotter. And on all 'mechs they can be used in an indirect tactical sense, as a method of making otherwise viable areas untraversable or at least uncomfortable to traverse.
Virtually every 'mech I have that has missile hardpoints, I've tried LRMs as at least part of the missile loadout, and most of them I've kept- they're just too useful, as long as the pilot understands the limitations (absolute range, minimum range, flight arc). For me, at least, they get more useful all the time as I learn more about things like how close I should be to hit with LRMs under certain ceilings, or which hardpoint on a given 'mech is mounted high enough to launch over this or that bit of terrain.
I have no idea how to end this post, so here's a pair of robotic pants.