The list of sports at a Summer Games changes from edition to edition. The mechanism behind those changes is a set of hard caps rather than a judgement about sporting merit.
The programme operates under a ceiling
Limits exist on the total number of athletes, the number of events and the number of days, because every one of those drives cost for the host city.
Accommodation, transport, officiating and security all scale with athlete numbers, and a Games that grows without limit becomes unaffordable to stage.
Adding anything therefore requires removing something of comparable size, which is why the debate is always comparative rather than about a sport in isolation.
Host cities can propose additions
Organisers are permitted to put forward extra sports for their own edition, chosen for local popularity and existing facilities.
Because the addition is tied to that Games, a sport can appear once and vanish, which is why the programme differs between editions in ways that look arbitrary.
The advantage for the host is genuine: a sport with a domestic following sells tickets and attracts a local broadcast audience that an unfamiliar one cannot.
Removal criteria are mostly commercial
Sports are assessed on television audience, ticket sales, global participation, governance and anti-doping compliance.
A sport with strong participation but weak viewership is vulnerable, because broadcast rights fund a substantial share of the whole event.
Governance failures have removed sports independently of their popularity, since the organisation running a sport is judged alongside the sport itself.
New sports are chosen for audience age
Recent additions have tended towards disciplines with young participants and existing followings outside traditional sporting media.
The reasoning is straightforward: the audience for the Games has been ageing, and sports that reach younger viewers address that directly.
These additions also tend to need temporary venues rather than permanent ones, which suits hosts trying to avoid facilities with no use afterwards.
Why federations fight so hard for inclusion
Olympic status determines government funding in many countries, because national sports budgets are frequently allocated around medal potential.
Losing inclusion can therefore remove the financial basis for a sport's entire national programme, well beyond the Games themselves.
That is why removal decisions produce responses out of proportion to a fortnight of competition, and why federations reform governance quickly when their place is questioned.