Alright, look..
1) Technomancers are the 'ghost in the shell' . What I mean by this is that they are not guys who just pound pound pound pound on the door like a decker does. Especially at the start. Like I showed earlier, doing Static Veil and then sustaining it with your focused concentration or a sprite can enable you to spend hours, connected to the net after your GOD score started. Because now, it doesn't increase at all. Once a Decker's GOD score starts, there is little they can do to stop it beyond rebooting.
Now that you can wait indefinitely watching the castle grounds, you don't have to start running up screaming with your battering ram to take it on like deckers do. You can wait for the right opportunity because now you have time to look for that opportunity. Granted your team might not have the time, but they might not really have the time for a decker to reboot his deck in mid operation. Unlike the decker though, you have a powerful tool in your hands. You have Choice.
2) They are called /techno/mancers. not /ludite/mancers. Sometimes you will need to use technology to solve problems. Sometimes using a bit of it here and there actually would allow you to do things beyond your normal capabilities.
For example you bring up Jammers as the defacto of all the noise that will ever happen. Implying that a decker has some magical abilities to interface with things wirelessly without suffering the effects of a Jammer. And the technomancers magical abilities can't do anything against it either, oh wait.. You are not a device. And Jammers only affect devices. So.. yeah. Seems your magical abilities do actually ignore jammers.
And the same thing with Head jammers. There is like literately no possible way to /stop/ you from technomancing beyond beating the snot out of you or killing you. But at long as you're not /stupid/ and do things to avoid getting caught being a technomancer, there is also no way to detect that you even are one.
Though if you still must run agents, then yes, get a deck to run one or two of them. But you're not chained to that deck.
3) You are a biological machine.
What this means is there are /ways/ of augmenting yourself without augmenting yourself.
Namely I'm speaking of Drugs.
Need +1 on your sleeze? Take Cram, Jazz
Need +1 on your Firewall? Take Deepweed. Kamakazi
Need to run for four days straight? Long Haul
Need +2 to firewall? Nitro
Need +1 to attack? Novacoke
Need +1 Data Processing +1 to Sleeze? Psyche
Not that I'm saying take these all the time. They do come with their own problems, obviously.
4)
Looking at the best cyberdeck.. Its got
9,8,7,6 for its stats. Assuming you run a program for each of those stats, You're looking at 10, 9,8,7.
With a human Technomancer who doesn't want to use up any of his essence to enhance his brain deck, the best you can do is 6,6,6,6.
Oh, but now you go and spend 28 karma (or 14 at character creation) to raise your max attribute
for any of your stats, by 1. Now you can achieve 7,6,6,6.
You can submerse then 8 times, I know, that is a lot of karma, but what they used there is a lot of money. Doing this gives you 9,8,8,8 And 4 more submersions gives you the four programs that are 'so dreadfully important, giving you a 10,9,9,9 brain deck.
granted you've got to raise your resonance to get that high, but at the other poster pointed out, Resonance really isn't that important that you need every last drop. Meaning you can take cyberware and bioware.
First off is his Pain Editor. And if you wanted to, you could take the Cerebral booster, giving you either 14,9,9,9 or 10,13,9,9. Throw in a few drugs, and you can do all sorts of boosts to your brain deck.
Best of all, it doesn't just stop there. The decker has hit his limit. He cannot progress any further at all. The Technomancer can however. You can keep submersing, increasing your resonance, increasing the number of programs ran at once, even increasing the bioware and cyberware you'd want. Though you really don't need anymore I think.