Arrow has many problems but none greater than Olicity (Oliver & Felicity). Two and a half seasons ago the show made the decision to stir the series towards a fan-fueled vision, completely risking its prior success and everything else. And boy, has it paid off over the years (bad ratings, bad reviews, bad show). Here is how Olicity managed to turn a promising show into a terrible circus:
1. Too much energy and focus is spend propping the ship to do much justice to other characters and relationships. The Olicity relationship has consumed the show for the past two & half years and they weren't even really together then.
2. Nearly every character is used to prop Olicity. The characters have been used as propping pieces and ship mascots than humans with their own worth and wants. Big bads end up looking like jokes because they are so enamored with Felicity/Olicity . It just makes the show so unbelievable and unrealistic.
3. Oliver and Felicity characters are written OOC, they no longer care for anything other than themselves and their so called epic true love. Oliver shows no respect for anyone other than Felicity now, that's our hero alright. Two of the best characters in the show have been turned into total juveniles and jerks.
4. Oliver's regression. Originally Oliver is a flawed personality but now he has no redeeming qualities. With the Olicity romance, Oliver has become so much more irrational, incompetent and selfish. Oliver Queen is turned into a humorless, stupid and an extremely messed up personality to highlight Felicity as better for him, his "light". Olicity is hailed as to be the best relationship for Oliver yet ironically he is the worst he has even been with her.
5. Sexism directed at Oliver's other loves interests to prop as Fel the one. Other female characters are written as less worthy and special. Fel was once the show's happy accident but now she has been emerging as a terrible addition. Characters are sacrificed at her and Olicity's altar, especially female ones.
6. Felicity Smoak is less likable. Olicity has negatively affected Felicity too. Felicity turned from a strong willed, intelligent and well rounded character into a mindless 'fool for love', who only has a man's interests on the brain. Her agency, intelligence and assertiveness has taken a huge nose dive for Oliver/Olicity. Her once endearing personality has since become repulsive due to her actions concerning Oliver. Felicity gave up an equal and healthier relationship with Ray Palmer, for a one sided and unhealthy one with Oliver. Doesn't sound completely sane but that's consistent with anything Olicity related.
7. The characters' actions and show make very little sense. Oliver & Felicity don't have to earn anything anymore and rarely face repercussions for their actions . Olicity is also more about telling than its is about showing. They are sold as selfless heroes and good relationship, even though there is no back to that. They don't have to do anything to earn their rewards and praises.
8. The ship eats up screen-time that could go to other characters and you know, make the show better and well rounded. Many interesting guest characters, who could easily have helped to enrich the show were shipped out, so the show could retains its Olicity focus.
9. Erasures & retcons - I could write a whole book about this. The writers show little respect for their canon, characters and relationships. They continually use retcons to prop Olicity, making that their top priority & end goal. Most of Olicity dialogue reeks of a fake aura, LOL duh, its because its totally fake or retconned.
10. Credibility & quality lost. Arrow has turned into a fake show. Olicity vision and POV rules this show. There is no realistic and truthful storytelling anymore. Good relationships and characters are changed or suppressed to show Olicity in the best light. The popular choice has clearly won over the right choice(s) for the series. A fake show is worse than a bad show, that is what Olicity has turned Arrow into - FAKE. This is possibly the worst crime of Olicity to this series.
Olicity is a major problem the show doesn't want to fix nor do they care to acknowledge its damaging effects. Thanks to Olicity, the future of the series has never been bleaker.