after having dueled a friend's test build with this (both with hybrid agents and with mirror match 8D), i kind of agree but kind of do not. it's not so much that any of the cards will be dead as that sometimes they don't form any useful plays; in general all the main monsters are pretty good.
imo seth, usir/osiris and tefnut are all unnecessary in this deck, tefnut clogs and can't attack if it's summoned while seth/osiris can't be run in large numbers which makes them inconsistent (osiris banishes your holy seals for summoning which is really bad). it should be focused on tributing into shu/nephthys for control and beatdown, and using geb/dragorado to pull the holy seals to facilitate fast level 8 plays off isis, which lets you exert loads of pressure with ennead. r5 plays would be a secondary option since nephthys and isis are both 5*; atem is powerful but difficult to summon because shu is the only 6*.
in other words, i'm seeing the primary four hieroglyphs as geb, isis, shu and nephthys. the rest of the maindecked monsters aren't so hot.
superstrength is an unnecessary minus when most of the monsters can be ss'd; the tribute floating will compensate for that card economy but superstrength has no such benefit. best tribute cards to play in this deck afaik are Enemy Controller, Burst Breath and seal of obliteration/erasure.
as for other useful cards, Trade-In imo is unavoidable (duality isn't too hot because too many plays will involve tribute special summoning). dragorado opens a lot of combos and also enables BLS but i can't say for sure if it's worth it, since dragorado can be a bit inconsistent - worst case scenario, dragorado serves as a 2100 beater. Red-Eyes Darkness Metal Dragon is another interesting tech whose usefulness i cannot confirm; atem is difficult to bring out and without it REDMD is also a mixed bag to summon, but the main monsters can all be ss'd by it which is nice. definitely has its uses though. honest is a must include. i'm mixed on Champion's Vigilance because the 8* seals are so easy to kill, but i'm leaning towards yes atm since you leave them in faceup defense more often than one might expect.
since it's always easier to edit other people's work, here is the build i was testing in the mirror match with that friend of mine - i only used it once or twice so i cannot confirm that it's any good, but it's a start. side deck is generic and the extra is just loaded with any monster i can make.
the full extra, if curious, is
1 gustaph max (for the two REDMDs i run. that little 2k can be game sometimes)
1 thunder end (yes you really can use up this many rank 8s in a single duel)
2 atem (prob gonna cut to 1)
1 sacred pleaides
1 daigusto emeral
1 lavalval chain
1 chimeratech fortress (because without maindecked tuners, this extra is really not cramped at all)
cards i'm contemplating in maindeck atm: avarice (since you can tribute really fast in this deck), third nephthys (in exchange for third isis, most likely) are the ones i'm thinking about the most atm
EDIT: had some interesting realizations while dueling a friend's hieroglyphs. if this deck has no monsters on the field, it's almost impossible to survive while topdecking - the combos all require a monster to summon and a monster to tribute, at the minimum. the only ways out are geb and tefnut, or boss monsters. i'm probably gonna run gorz and trag in my build above to compensate (trag especially since it makes exceed plays 8D) another good option in that regard, if a disaster dragon engine is used, would be Totem Dragon.
y would u drop atum down to 1 u need him at three to get the gustaph plays
and to swarm the field for otk potential
main reason i would not run Luster Dragon #2 or any non-hieroglyph normals in general is because they don't have any synergy with geb, and geb is frankly what makes this deck work. i suppose you could run only one of the hieroglyphic seals but i'm not loving that idea; if the only one you have gets banished somehow then you'd be in trouble. either way all the normal monsters in this deck are vulnerable to chain dis (since they're all 0/0 when summoned) so there's no real advantage to running non-archetype normal monsters, unless you're running Totem Dragon. the exception perhaps is blue eyes because it has a support card of its own (white stone of legend) but i'd still prefer hieroglyphic seals
EDIT: and as for bls, dragorado provides more than enough fuel combined with any dark tech you might run like REDMD or gorz/trag, so tri-horned being a dark monster doesn't really make it worthwhile
gebeb is great i will grant that but runing Luster Dragon #2 and some other lvl 6 vanilla monster is for the atum plays and the fact that ur opponent will be maining atleast 2 Chain Disappearance so u need to run different monsters of the same lvl and that r vanilla monsters to get around chain