To play devil's advocate, many/most clubs across the top divisions in the main leagues have incomes measured in the £hundreds of millions. They choose to spend the bulk of their player wages budget on a core of perhaps 12-18 top-end players (I'm talking relatively) on high salaries, filled out with players a quality-tier down but still on very good salaries. Looking at just the PL, annual individual wages of £5m are commonplace, with a fair number on £10m+. A year. Every time more money comes into the sport (increased TV deals) that hasn't generally been used to lower ticket prices for fans or the like, it increases the average salary of players.
If clubs chose, they could have a squad of 25 players of roughly similar ability, all interchangeable to rotate and keep fresh, even with internationals. An few injuries and it makes little difference in terms of overall quality of the XI on the pitch. But they don't. They lump on a much smaller group of first-choice players, then experience a fall-off in quality when a first choice players gets injured.
Of course, the other side of the coin - and the reason clubs don't do the above - is that there will always be clubs seeking that competitive advantage of packing their first choice XI with better, more expensive players. And with artificially-funded plastic clubs like Abu Dhabi and Qatar Saint Germain throwing dirty money around to try to buy success (and sportwashing) it'd be impossible to try to get clubs to take a more sensible approach to a bigger squad of comparable quality players that can be rotated.
So yes, the scale of internationals is ridiculous and putting dangerous physical pressure on many players. Yes, football federations are greedy (historically with corrupt officials). Yes, international football outside of mainline competitions and qualification should have been suspended in a global pandemic. Yes, players need to realise their physical limits and be both able and willing to miss some international (especially friendlies) to R&R.
But also clubs and the way they set their player rosters up should not be absolved of contributing to player burn-out and increased chance of injury.
This is notwithstanding that international friendlies this year should have been cancelled during a pandemic.
