everything you said=untrue
Architect is a must in every AtD game cuz of it's defenses,it makes DK's summons less usefull,and vastly increases ur DPS done to DK
I think its near impossible to have any chance vs DK if you are just a lonely architect
Obviously when building a base 3-4 heroes should defend it or else ur screwed if DK finds ur base(and he prolly will if he isnt a tard), one of the best places to build a base(IMO) is near the portal to the drakes( cant remember name ,havent played for a long time), you can have 1 way entrance there easily and space to build towers ,plus you get to kill drakes and get a usefull item(if dk gets it ur screwed),
one of the most common mistake i 've seen is ppl build right away at level 1/2 as architect,this is wrong,you have almost no gold and DK just feeds off your buildings cuz ur party cant rly defend it, gather up some gold,get LVL 3(the party members should all b level 3 i think), clear creeps on portal if they havent been crept, and build base.
Leave one space and have a hero(not architect) tank the DK,then switch with other ,or have hunters dog tank, the essential thing is not to have DK wrecking your tower when u have build teh base,last one to tank should be architect if everyones on red or healing.
After doom main thing to do is not to panic,yes sure DK got lots of powerfull units but its bearable, you should have decent items by the time doom starts and level around 3-4ish(5 is rly good),dont forget to get pots and switch tanks,also architect should not die or this game is over(unless u manage to survive somehow,run i think?)
All of this ,though, cant be done if you have shit architect or noob party who cant level , you can do this if you have good architect and one good ranger(hunter or druid), and just carry other heroes with you and lvl up
anyways i cant give too much specific information cuz i havent played for a long time, but from what i 've played,i can say that its possible to survive the doom if your party is somewhat decent