(Answered) ECM vs TAG, I don't get how these 2 systems interact

[Bleh!]

Sorry actual question down below in second post, I've deleted this as it was just late night confused rambling.

[Bleh!]

Nevermind, I knew I should of just slept on it, I think I just got hopelessly confused earlier. I'm kind of embarrassed by my above question I just couldn't believe how crazy powerful ECM seems in the board game compared to the how the computer game portrays it as.

So if I'm understanding the ECM rules correctly. You need a Targeting computer or TAG to even shoot an ECM equipped mech or mechs under the ECM bubble with various weapons if you are not adjacent to them. So a Targeting computer and or TAG is pretty much must have pieces of equipment on every mech, because why wouldn't you and your opponent have at least 1 mech in each of your force take ECM as its only 1.5 ton and a piddly 61BV for potentially such a powerful advantage. While trying to counter ECM can require either a pretty hefty targeting computer in both tonnage and BV depending on how many weapons are on the mech mounting it. Or you go the slightly cheaper missile route with a TAG that will miss every now and again preventing you from attacking the ECM mech or any mechs under the ECM bubble. Am I understanding this correctly?

[Xotl]

ECM does not block LOS at all.
It counteracts a select few pieces of equipment.  On page 134 of TW, (and page 112-113 of BMM) the pieces of equipment are specifically listed.
It only affects those items.  It affects nothing else.

LOS is mentioned because of how ECM works:

Let's say you're using Artemis IV.  Your Line of Sight to your intended target traces through the ECM bubble of a hostile 'Mech.  This means you lose the +2 bonus on the Cluster table, causing your attack to work just as if you'd brought no Artemis IV at all.  Beyond that, you suffer no penalties.  The attack proceeds normally, without the bonus.
Items not affected by ECM don't care whether you have ECM or not.  They work normally.

[Bleh!]

Thanks for the clarification.